Fabrication Of Array-analytic Ultrasonic Focused Transducer

Focused ultrasound transducer is the core component of ultrasound microscopy，it plays a very important role on ultrasound imaging scanning and the measurement ofacoustic properties of materials in the industrial field. With the development ofindustrial technology and material science, focused ultrasound transducers alsochange to higher frequency, higher accuracy and higher resolution. However, theconventional ultrasonic transducers all use a single piezoelectric sensing element, allof the obtained signal which reflected from the specimen, is the energy integral of thepiezoelectric surface. So it is hard to describe the space distribution characteristics ofthe reflected sound field. Therefore, it is urgent to develop an arrayed acoustic sensingmode to sense the focused sound field from the multi-angle, to restore the distributionof reflected sound field better. This paper focuses on the problem of sound fieldsensing, and designs the analytic-array focused ultrasound transducer, and alsostudied the corresponding theory and experiment. The main contents are as follows:(1) As the conventional focused ultrasonic transducer using a single sensingelement, it can hardly describe the distribution of acoustic field, combined theformation mechanism of the back reflection of the sound field, it develops a new typeof focused ultrasound transducer, called analytic-array focused ultrasound transducer.It designed by gel spin coating, UV exposure, micro and nano electron beamevaporation and other precision machining technology, to realize to make arraysensing elements on a large opening angle of the focus lens. It also used thehigh-temperature sol crystallization of P(VDF-TrFE) to achieve the array sensingelements of piezoelectric material. In the end, it produced a new kind of sound fieldsensing transducer which the excitation and reception are separated.(2) It also builds a high-speed ultrasonic testing system based on FPGAtechnology, and calibrated the excitation and response of the analytic-array ultrasoundfocused transducer with this system. Combined with the finite element simulation ofthe no defects model, it analyzes each sensing element`s performance in theexperiment, and gives out the correction coefficient of every element. Finally, it matches the results of the experiment and the finite element simulation.(3) By sensing the distribution characteristics of the sound field and processingthe sensing signals from different angles, it carries out experimental studies on theheight testing of the vertical boundary using this new transducer, which shows theexpected results matching with the finite element analysis. This solves the problemthat the conventional ultrasound cannot be achieved the height, so it means theanalytic-array focused ultrasound transducer has better academic significance andapplication value.