检索结果-内蒙古大学图书馆

IEEE International Ultrasonics Symposium (IUS)

作者： Qiu, Yongqiang Wang, Han Bolhovitins, Aleksandrs demore, Christine Cochran, Sandy Gebhardt, Sylvia Schoenecker, Andreas Univ Dundee Inst Med Sci & Technol Dundee Scotland Fraunhofer Inst Ceram Technol & Syst Dresden Germany

ISBN: (纸本)9781467356862

This paper reports the fabrication and evaluation of a two-dimensional thick film PZT ultrasonic transducer array operating at about 7.5 MHz for particle manipulation. All layers on the array are screen-printed and sintered on an Al2O3 substrate without further processes or patterning. The measured dielectric constant of the PZT is 2250 +/- 100, and the dielectric loss is 0.09 +/- 0.005 at 10 kHz. Finite element analysis has been used to predict the behaviour of the array and impedance spectroscopy and laser vibrometry have been used to characterise its performance. The measured deflection of a single activate element is on the order of tens of nanometres with 20 V-pp input. Particle manipulation experiments have been performed by coupling the thick film array to a capillary containing polystyrene microspheres in water.

关键词： Thick Film Screen-printing 2-d array Particle Manipulation

来源：评论

学校读者我要写书评

暂无评论

Practical S-Sequence Aperture Coding Schemes for Volumetric Imaging with Top Orthogonal to Bottom Electrode (TOBE) arrays

Practical S-Sequence Aperture Coding Schemes for Volumetric ...

引用

IEEE International Ultrasonics Symposium (IUS)

作者： Zemp, Roger Ceroici, Chris Harrison, Tyler Univ Alberta Dept Elect & Comp Engn Edmonton AB Canada

ISBN: (纸本)9781479981823

Recently Top-Orthogonal-to-Bottom Electrode (TOBE) 2d CMUT arrays were introduced. These arrays offered the possibility of 3d imaging without requiring a fully-wired array, however, previously proposed imaging schemes suffered from speed or resolution limitations. Here we propose a new imaging scheme which we call Fast Orthogonal Row-Column Electronic Scanning (FORCES). This new approach takes advantage of the bias-sensitivity of CMUTs to enable high-quality and fast B-scan imaging.

关键词： 3-d imaging 2-d array CMUTs Crossed-Electrode array

来源：评论

学校读者我要写书评

暂无评论

Real-Time Volumetric Imaging System for CMUT arrays

Real-Time Volumetric Imaging System for CMUT Arrays

引用

IEEE International Ultrasonics Symposium (IUS)

作者： Choe, Jung Woo Oralkan, Oemer Nikoozadeh, Amin Bhuyan, Anshuman Lee, Byung Chul Gencel, Mustafa Khuri-Yakub, Butrus T. Stanford Univ Edward L Ginzton Lab Stanford CA 94305 USA

ISBN: (纸本)9781457712524

We designed and implemented a flexible real-time volumetric ultrasound imaging system for capacitive micromachined ultrasonic transducer (CMUT) arrays, consisting of an ultrasound data acquisition system, an FPGA board, and a host PC. The system works with arbitrary-shaped CMUT arrays and non-standard beamforming methods, as well as with regular-shaped CMUT arrays and conventional beamforming methods. In this paper, we present the system design and real-time imaging results obtained using this system with a ring array, a rectangular array, and a linear array. In synthetic phased array (SPA) imaging with a 64-element ring array, we could display 3 image planes with a total of about 70,000 pixels in real time, at a frame rate of 9 frames per second (fps) which was limited by the computational load on the CPU required for synthetic beamforming. On the other hand, the frame rate in classic phased array (CPA) imaging is limited by the data transfer time. In CPA imaging with a 16x16-element rectangular array, a frame rate of 5.4 fps was achieved for 1,250 acquisitions per frame and a 2.5-cm imaging depth. The frame rate can be increased by reducing the number of pixels processed in SPA, or by reducing the number of beams received in CPA, at the expense of degraded image quality or reduced field of view.

关键词： CMUT Real-time imaging Volumetric imaging Ring array 2-d array

来源：评论

学校读者我要写书评

暂无评论

Small-pitch flip-chip-bonded VCSEL arrays enabling transmitter redundancy and monitoring in, 2-d 10-Gbit/s space-parallel fiber transmission

引用

IEEE JOURNAL OF SELECTEd TOPICS IN QUANTUM ELECTRONICS 2007年第5期13卷 1279-1289页

作者： Roscher, Hendrik Rinaldi, Fernando Michalzik, Rainer Univ Ulm Inst Optoelect D-89069 Ulm Germany

We demonstrate novel pixel architectures in 2-d vertical-cavity surface-emitting laser (VCSEL) arrays offering additional functionality without sacrificing efficient fabrication, compactness, and low module cost. Very high flip chip VCSEL packing densities enable both a built-in 3-per-channel VCSEL redundancy as well as simple intracell VCSEL monitoring. Each pixel has three individually addressable oxide-confined and substrate-removed 850-nm-wavelength VCSELs directly flip bonded to the mesas that are extremely close-spaced to permit equal butt coupling to 50-mu m-core-diameter multimode fibers (MMFs) without the need for external coupling optics. Built-in radial VCSEL-to-fiber launch offsets as small as 7.8 mu m were reached, leading to offset coupling penalties of only 0.4 dB. Quasi-error-free transmission of 10 Gbit/s signals is achieved over 500-m-long MMFs even under offset launch conditions. New opportunities for a range of further applications offered by high-density VCSEL arrays are discussed.

关键词： 2-d array data transmission flip chip bonding optical interconnect redundancy space-division multiplexing vertical-cavity surface-emitting laser (VCSEL)

来源：评论

学校读者我要写书评

暂无评论

SEPARABLE BEAMFORMING FOR 3-d SYNTHETIC APERTURE ULTRASOUNd IMAGING

SEPARABLE BEAMFORMING FOR 3-D SYNTHETIC APERTURE ULTRASOUND ...

引用

IEEE Workshop on Signal Processing Systems (SiPS)

作者： Yang, Ming Sampson, Richard Wenisch, Thomas F. Chakrabarti, Chaitali Arizona State Univ SECEE Tempe AZ 85287 USA Univ Michigan Dept Elect & Elect & Comp Sci Ann Arbor MI 48109 USA

ISBN: (纸本)9781467362382

Recently, there has been great interest in 3-d ultrasound imaging, but power constraints have precluded practical implementation of high-resolution 3-d ultrasound in handheld imaging platforms. In this paper, we propose a separable beamforming procedure for subaperture-based 3-d synthetic aperture ultrasound systems that drastically reduces computational (and hence power) requirements. Separable beamforming approximates 2-d array beamforming through a series of 1-d beamforming operations. Our proposed method is based on a separable delay decomposition method that minimizes phase error. We show that the proposed separable system achieves 19-fold complexity reduction while producing images with contrast-to-noise ratio comparable to that of non-separable systems. Furthermore, we propose an online iterative delay calculation method that substantially reduces storage requirements. We briefly describe how the separable beamformer can be implemented in the context of Sonic Millip3de, our recently proposed hardware accelerator for the digital front-end of a 3-d ultrasound system.

关键词： Separable beamforming separable delay 2-d array hardware implementation

来源：评论

学校读者我要写书评

暂无评论

1 W frequency-doubled VCSEL-pumped blue laser with high pulse energy 14

1 W frequency-doubled VCSEL-pumped blue laser with high puls...

引用

Conference on Solid State Lasers XXIV - Technology and devices

作者： Van Leeuwen, Robert Chen, Tong Watkins, Laurence Xu, Guoyang Seurin, Jean-Francois Wang, Qing Zhou, delai Ghosh, Chuni Princeton Opt Inc Mercerville NJ 08619 USA

ISBN: (纸本)9781628414325

We report on a Q-switched VCSEL side-pumped 946 nm Nd: YAG laser that produces high average power blue light with high pulse energy after frequency doubling in BBO. The gain medium was water cooled and symmetrically pumped by three 1 kW 808 nm VCSEL pump modules. More than 1 W blue output was achieved at 210 Hz with 4.9 mJ pulse energy and at 340 Hz with 3.2 mJ pulse energy, with 42% and 36% second harmonic conversion efficiency respectively. Higher pulse energy was obtained at lower repetition frequencies, up to 9.3 mJ at 70 Hz with 52% conversion efficiency.

关键词： vertical-cavity surface-emitting laser diode-pumped solid-state laser blue laser 808 nm 2-d array high power high pulse energy 946 nm

来源：评论

学校读者我要写书评

暂无评论

Fabrication-Efficient Flip-Chip-Bondable 850-nm VCSELs With an X-Shaped Vertical Cavity

引用

IEEE JOURNAL OF SELECTEd TOPICS IN QUANTUM ELECTRONICS 2013年第4期19卷 1700810页

作者： Roscher, Hendrik Michalzik, Rainer Univ Ulm Inst Optoelect D-89081 Ulm Germany

We present a novel approach to flip-chip-bondable vertical-cavity surface-emitting lasers and 2-d arrays emitting at 850 nm, the standard for multimode fiber optical interconnects. A unique sequence of wet-etching steps renders laser fabrication particularly efficient and allows the incorporation of near-cavity heat spreaders. Record-low thermal resistances of substrate-removed devices are achieved without compromising the dynamic properties.

关键词： data transmission fabrication technology flip-chip bonding optical interconnect semiconductor laser space-division multiplexing thermal resistance vertical-cavity surface-emitting laser (VCSEL) 2-d array

来源：评论

学校读者我要写书评

暂无评论

Improved spatial resolution in a three-dimensional acoustic medical imaging system based on a hybrid method using a synthetic aperture technique

引用

JAPANESE JOURNAL OF APPLIEd PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 2007年第7B期46卷 4827-4833页

作者： Taki, Hirofumi Sato, Toru Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan

For an acoustic real-time three-dimensional (3-d) imaging system with high spatial resolution, we propose a system based on a hybrid method using a synthetic aperture technique. We can change the transmit point in this system;thus, the coherent integration of multiple receive signals from different transmit points improves spatial resolution using a synthetic aperture technique. In the case of a time resolution of 300 3-d images/s, the -3 dB lateral resolution of the proposed system is 1.30 lambda in the x-z section and 1.17 lambda in the y-z section for a 0.07 m depth, where the lateral resolution is improved from 16 transmit and receive events. The number of elements can be reduced to about 1/7.5 of a dense two-dimensional (2-d) array of a digital beamforming imager having the same time and spatial resolution.

关键词： ultrasound hybrid method real-time 3-d imaging reflector 2-d array synthetic aperture digital beamforming phased array

来源：评论

学校读者我要写书评

暂无评论

Thick Film PZT Transducer arrays for Particle Manipulation

Thick Film PZT Transducer Arrays for Particle Manipulation

引用

IEEE International Ultrasonics Symposium

作者： Yongqiang Qiu Han Wang Aleksandrs Bolhovitins Christine demore Sandy Cochran Sylvia Gebhardt Andreas Schonecker Institute for Medical Science and Technology University of Dundee Fraunhofer Institute for Ceramic Technologies and Systems

ISBN: (纸本)9781467356855

This paper reports the fabrication and evaluation of a two-dimensional thick film PZT ultrasonic transducer array operating at about 7.5 MHz for particle manipulation. All layers on the array are screen-printed and sintered on an Al_2O_3 substrate without further processes or patterning. The measured dielectric constant of the PZT is 2250 ± 100, and the dielectric loss is 0.09 ± 0.005 at 10 kHz. Finite element analysis has been used to predict the behaviour of the array and impedance spectroscopy and laser vibrometry have been used to characterise its performance. The measured deflection of a single activate element is on the order of tens of nanometres with 20 V_(pp) input. Particle manipulation experiments have been performed by coupling the thick film array to a capillary containing polystyrene microspheres in water.

关键词： Thick Film Screen-printing 2-d array Particle Manipulation Screen printing Sensor arrays thick films Piezoelectric ceramics Nanometers Films dielectric losses arrays ultrasonic transducer arrays

来源：评论

学校读者我要写书评

暂无评论

Synthetic Aperture 3d Ultrasound Imaging Schemes with S-Sequence Bias-Encoded Top-Orthogonal-to-Bottom-Electrode 2d CMUT arrays

Synthetic Aperture 3D Ultrasound Imaging Schemes with S-Sequ...

引用

IEEE International Ultrasonics Symposium

作者： Alexander Sampaleanu Roger Zemp Department of Electrical and Computer Engineering University of Alberta

ISBN: (纸本)9781467356855

Crossed electrode arrays, wherein electrodes are connected in individually addressable rows and columns, have been previously investigated as a means to reduce the number of channels in two-dimensional ultrasound arrays for three-dimensional imaging. Previously envisioned imaging schemes have been limited in their resolution and focusing ability due to their inability to perform active focusing in both the lateral and elevational direction for both transmit and receive. As well, signal-to-noise ratio (SNR) can be compromised when transmitting or receiving on only one row or column at a time. A new imaging method is proposed for this array architecture using capacitive micromachined ultrasound transducers (CMUTs) which can provide two-way focusing in both lateral and elevational directions while providing optimal SNR. This method is a variation of synthetic aperture imaging wherein the columns active upon transmit and receive events are determined by applying a bias to specific columns upon transmission and reception in an S-sequence encoded pattern. Mathematical derivations of this method are presented and simulations are done to compare this imaging method to previously published crossed-electrode array imaging schemes, as well as to fully-populated 2-d phased array imaging.

关键词： 3-d imaging 2-d array CMUTs Crossed-Electrode array Three dimensional imaging TRANSMITTING signal to noise ratios array structure Synthetic aperture Imaging Lateral Ultrasonography electrode configuration FOCUSING arrays

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：