I am designing a piezoelectric transducer [probe] for use with an ultrasonic flaw detector to find cracks or holes in metal or inspection of welding. The crystals I am using aren't very good. They don't provide high enough gain, resolution or sensitivity. Can somebody please help me in design of very good quality ultrasonic probe? Also, a few years ago I used verntron piezoelectric crystal, made in England. Does anyone have contact information for the company that produces those crystals?