Study On Ultrasonic Focusing Phased Array

In recent several decades, ultrasonic phased arrays had been applied to many medical specialties and nondestructive evaluation (NDE). An ultrasonic phased array consists of multiple elements which are usually cut or etched from a single piezoelectric plate of Lead Zirconate Titinate (PZT). The element thickness determines the operating frequency of the transducer. Another material frequently used is polyvinylindene fluoride (PVDF), which is a polymer being able to exhibit piezoelectric properties. The elements are individually excited at predetermined time delays to dynamically steer or focus the acoustical wavefronts. The steering and focusing characteristics of an array is determined by its geometric parameters. In analyzing the characteristics, phased arrays at first are considered as an array of simple point sources arranged in the azimuthal plane. This approach is mathematically easier to deal with, yet it gives the same directivity in the azmuthal plane. However an actual array always have finite dimensions. Second the model of array was considered to have elements of finite width and infinitely large elevation dimension. This model ignore the effect of elevation on beam focusing. This paper study on phased array which was considered to have elements of finite width and finite elevation dimension, the influences of transducer parameters on focusing effect is analy/ed, including the number of elements( N ), interelement spacing(d), elevation dimension( L), width dimension( ). All this can be a fundament for deeper investigate phased arrays. At the same time, the concentric-ring transducers are also analyzed. It can realize point focusing on its axis. (1). Study on radiate sound field of rectangled plunger phased array:1. By uses of Relay's integrate, the pressure distribution of radiate sound field by rectangled plunger was derived, the directivity of wavesteering also was discussed.2. The analytical pressure distribution of ultrasonic phased array for the beam focusing was obtained using the Huygen s principle, By use of computer software, the pressure distribution was plotted.3. By means of numerical method, the influences of transducer parameters on focusing effect is analyzed, including the number of elements(N), interelement spacing(d), elevation dimension( L),width dimension( ).4. Study on the beam steering of phased array in far field.(2). Study on radiate sound field of concentric-ring plunger phased array:1. By uses of Relay's integrate, the pressure distribution of radiate sound field by ring plunger was derived, the directivity of wave steering also was discussed.2. Study on near-field properties of ring plunger.3. The analytical pressure distribution of ultrasonic phased array for the beam focusing was obtained using the Huygen s principle, By use of computer software, the pressure distribution was plotted.(3). Circuit Design:1. Introduce the digital electronic emitting system.2. Production and achievement of digital system.3. Measure and receiving system of phased array transducer.