Research On Ultrasonic Transducer Imaging System Based On LabVIEW

With the continuous development of acoustics,higher requirements are put forward for ultrasonic transducers and their test systems.Ultrasound transducer is the core device for ultrasound imaging.The core parameters of ultrasound transducer mainly include center frequency,frequency bandwidth,sound beam width,etc.,which require a variety of special instruments to measure.Various instruments are expensive and operate in different ways,which both cost money and lead to increased learning costs.Therefore,it is necessary to develop an ultrasonic imaging system integrating multiple functions to evaluate the performance of ultrasonic transducers.LabVIEW can easily connect and control the instrument,so it is necessary to develop an ultrasound transducer imaging test system based on LabVIEW.The main research contents of this paper are as follows:（1）Design and build the hardware and software architecture of the ultrasound imaging system.The hardware of the system mainly consists of gantry frame,high-speed data acquisition card,motion control card,servo motor and driver.The overall software framework of the system adopts the master-slave design pattern of standard state machine,queue message processor and user interface event processor.The software and hardware cooperate to realize the motion control module,the signal excitation module,the data acquisition module and the data imaging and optimization module.The scanning range of the system is 600×500×400 mm,and it has a variety of motion modes.The sampling rate of the acquisition module is 125 Msps,and the sampling resolution is 16 bit.It has a variety of trigger modes and is highly scalable.（2）The function of each submodule is realized through LabVIEW programming.A-mode echo imaging with an interval of 8 ns is achieved.B-mode cross-sectional imaging and C-mode three-dimensional surface imaging with a step accuracy of 5μm,a scanning speed of1 mm·s^-1,and a vertical depth of 60 mm and 40 mm,respectively,are achieved.Real-time scanning and imaging of a hydrophone with a two-dimensional step accuracy of 10μm and a scanning range of 200×200 mm can measure the amplitude and phase of the sound field.Multiple functions are integrated to complete the characterization of the acoustic performance of transducers below 30 MHz.（3）On the basis of conventional sound field measurement,the function of hydrophone is expanded,and two measurement methods are further proposed.One is to measure the amplitude and phase information of the sound field at all frequencies at the same time on the basis of the interval frequency of 0.1 MHz;the other is to measure the propagation process of the sound field wavefront at different times at each point on the basis of the interval time of 0.1μs.The expansion functions have been verified by simulation and experimental comparison,which meet the experimental needs and achieved the expected design goals.（4）The feasibility of the imaging test system is proved by specific experiments.First,COMSOL simulation and experimental tests were performed on a concave focused ultrasound transducer with a center frequency of 4.17 MHz and a bandwidth of 6.9%.The simulation of the sound field propagation process was consistent with the position and shape of the wavefront in the experimental imaging.The-6 d B transverse sound beam width of the experimental sound field amplitude decreases with the increase of frequency,and the change trend is consistent.Secondly,through experiments,it is found that the spectrum of the secondary echo has attenuation and offset,and the amplitude error between consecutive points is about 1/8,which makes the sound field amplitude map appear as light and dark intervals.Finally,an acoustic lens is designed using the angular spectrum theory,a custom sound field amplitude image is generated on the XY plane 3 cm away from the surface.The sound field amplitude of the target plane at 2 MHz is measured experimentally,and the experimental sound field diagram is basically the same as the design sound field diagram,which is in line with the theoretical and experimental expectations.