Research On High-precision Phased Ultrasonic Transmission In Phased Array Ultrasonic System

Ultrasonic phased array technique can help to achieve flexible, controllable synthesized ultrasound beam by exciting each element of an ultrasonic array transducer with independent phase delay. Phased array ultrasonic testing can accomplish dynamic focusing, obtain visual image, inspect component of complex geometry. Also it can improve detection sensitivity, resolution and SNR. But phased array ultrasonic testing system on hand has complicated structure, high cost and price, and it is difficult to safeguard, so an ordinary factory isn't afford to buy it, then it can't be extensively used in industry non-destructive testing (NDT).In this thesis, a 16-channel experimental high-precision phased ultrasonic transmission in phased array ultrasonic system is originally designed and developed, with the principle of phase array ultrasonic testing, multi-channel digital ultrasonic detector is reconstructed. So the detector can satisfy the requirement for phased array ultrasonic testing, and the phased array ultrasonic testing can be carried out.The thesis proves the time-delay precision and the independent channels'infection of phase launch by detailed researching the phase delay of ultrasonic phased array. And in the light of a 16-channel digital ultrasonic detector on hand, the thesis gets the testing basic requirement of 16-channel phased array ultrasound if the time-delay precision is less than 20ns.Concerning the key technology of phase delay, according to the time-delay precision requirement of 16-channel high-precision phased ultrasonic transmission in phased array ultrasonic systems, the principles and its implementation of digital phase delay based on pulse excitation is explained, and a 16-channel experimental high precision phased ultrasonic transmission in phased array ultrasonic system based on CPLD is designed, with the prerequisite of satisfying available 16-channel digital ultrasonic detector external trigger. Preliminary test and study showed that the delay time of the system is 10ns and the max is 2.55μs. Compared with the conventional delay methods, the delay method has many advantages, like in-phase, more sharp signal rise-time, higher in resolution of delay, longer in delay time and wider in adjusting range, etc., and the system can accomplish ultrasonic phased array transmission schemes.The development of high-precision phased ultrasonic transmission in phased array ultrasonic system for the experiment is considerably useful as a design reference for the spread of the phased array ultrasonic testing in NDT field and is helpful for the advance of the phased array ultrasound technique.