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3-Dimensional Acoustic Imaging by Multifrequency Hologram Matrix

多频全息矩阵三维声学成像

基本信息

批准号：
01460163
负责人：
MIYASHITA Toyokatsu
金额：
$ 2.88万
依托单位：
Sizuoka University (1990)Kyoto Institute of Technology (1989)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

Multifrequency holographic imaging method uses a two-dimensional spatial receiver (or transmitter) array for lateral two-dimensional resolution and a frequency array for range resolution to get a true three-dimensional resolution.First, we made a variety of computer simulations of three dimensional multifrequency holographic imaging, and confirmed that this method gives us a desirable true three dimensional resolution of the reconstructed images. That is, not only lateral but also range resolutions are both about 3.7 times wavelength of the central frequency of the frequency array.We designed and ordered two-dimensional acoustic transducer array to Nippon Denpa Kogyo Company Limited. Front size of the transducer is 80 mm times 80 mm. A large PZT plate of a good quality is cemented on the backing block made of Epoxy resin and metallic powder. Cutting it by a so-called diamond cutter, we made 16 times 16 (=256) receiver transducer elements of a small aperture of 1.0 mm times 1.0 mm, whos … More e spacing is 4.5 mm. Rest part of the pzt material is also composed of many small fragments of transducers. Those were connected electrically parallel to make a big size of transmitting acoustic transducer of 80 mm times 80 mm. This type of transducer structure is guaranteed to make a uniform piston oscillation and to transmit an ideal parallel plane wave to the object. Resonance frequency was designed to 600 KHz, and the frequency aperture of multifrequency hologram is designed from 450 KHz to 550 KHz. Therefore, sensitivity or gain and phase characteristics over this frequency range is very uniform and also mutual coupling between the adjacent elements is very small, i. e. -60 dB. These characteristics are very important for multifrequency holographic imaging of synthetic aperture method.Introducing a direct frequency synthesizer of a fast response, we modified the conventional control circuit of holographic measurement, and made it possible to measure multifrequency hologram in a desirable short time. i. e. 32 ms per frame, being directly controlled by a software of a minicomputer. This speed is necessary for medical imaging of living body.We designed and fabricated multi-channel preamplifiers for every receiver elements and simultaneously digitizing circuits for each raw of the matrix to make the measurement as fast as possible. Less

多频全息成像方法是利用二维空间接收（或发射）阵列实现横向二维分辨，利用频率阵列实现距离分辨，从而获得真三维分辨率的方法。首先，我们对三维多频全息成像进行了多种计算机模拟，证实了这种方法能够获得理想的真三维分辨率的再现像。我们为日本电波工业株式会社设计并订购了二维声换能器阵列。换能器正面尺寸为80 mm × 80 mm，压电陶瓷片粘接在环氧树脂和金属粉末制成的垫板上。通过所谓的金刚石切割机切割，我们制作了16 × 16（=256）个接收器换能器元件，其具有1.0 mm × 1.0 mm的小孔径， ...更多信息间距为4.5mm。PZT材料的其余部分也由许多换能器的小碎片组成。将它们电并联，制成80 mm × 80 mm的大尺寸发射声换能器，保证了换能器的均匀活塞振荡和理想的平行平面波发射。谐振频率设计为600 KHz，多频全息图的频率孔径设计为450 ~ 550 KHz。因此，在该频率范围上的灵敏度或增益和相位特性是非常均匀的，并且相邻元件之间的互耦合也是非常小的。e. -60分贝。这些特性对合成孔径法的多频全息成像是非常重要的，我们引入了一种快速响应的直接频率合成器，改进了传统的全息测量控制电路，使在较短的时间内测量多频全息图成为可能。I. e.每帧32毫秒，由小型计算机的软件直接控制。为了使测量尽可能快，我们设计并制作了每个接收单元的多通道前置放大器和矩阵的每个原始数据的同步数字化电路。少