DEVELOPMENT OF A MOMENT ECHOGRAPHY SYSTEM WITH A SINGLE ULTRASOUND SENSOR

在研究中，我们已经测试了一种新的声学传感器的可行性，该传感器具有基于新概念的空间分辨能力。在传感器中，单个信号通道连接到传感器，其灵敏度在孔径上进行空间调制。如果空间调制函数被设计成具有脉冲响应，我们可以从该脉冲响应中区分传播波前的方向和延迟，则我们可以使用检测到的波形来控制方向性。我们称传感器的孔径为“编码孔径”。该传感器可以在没有任何机械和/或电扫描的情况下操纵方向性。波束形成可以用完全数字和间接的方式来执行。此外，该传感器可以只通过一个发射和接收过程来获取数据。第一种方法使用了一个压电薄膜，其电极图案根据空间调制函数设计。第二种和第三种使用倾斜的1-D或2-D阵列编码的二进制序列。我们还提出了一种利用传感系统传播矩阵的伪逆的判别算子，并构造了5 MHz超声在水中和50 KHz超声在空气中的实验系统。当使用所开发的算子时，系统的PSF中出现的非期望峰值的相对水平小于-40dB。实验结果证明了该传感器用于二维超声成像的可行性。

In the research, we have tested the feasibility of a new acoustical sensor which have an spatial resolving ability based on a new concept. In the sensor, a single signal channel is connected to a transducer whose sensitivity is spatially modulated on an aperture. If the spatial modulating function is so designed to have an impulse response from which we can distinguish the direction and delay of propagated wavefront, we can control the directivity using the detected waveforms. We have called the aperture of the sensor "Encoding Aperture". This sensor can steer a directivity without any mechanical and/or electrical scanning. Beam-forming can be performed with an entirely digital ans indirect manner. Furthermore, the sensor can acquire data with only a single transmitting and receiving process.We proposed three implementations for the apertures. The first one uses a piezoelectric film with an electrode whose pattern is designed according to a spatial modulating function. The second and the third use an inclined 1-D or 2-D arrays coded with binary sequences. We also proposed an discriminating operator using a pseudo-inversion of the propagation matrix of the sensing system.Experimental systems using 5MHz ultrasound in water or 50KHz one in air were constructed. The relative levels of undesired peaks emerges in PSF of the systems were less than -40dB when the developed operator was used. The results demonstrate the feasibility of the sensor to the 2-D echography.