Scanning head with 128-element 20-MHz PVDF linear array transducer.

A scanning head has been designed and fabricated that incorporates a 20-MHz, 128-element linear transducer. The scanning head also incorporates -200 V pulsers and a custom 16-channel amplifier. The transducer was constructed with 28 microm PVDF film with an element pitch of 250 microm. The transducer showed an average -20 dB pulse length of 69 ns. The elements of the PVDF array were tested and found to have 7.5 mPa/ radical Hz equivalent noise pressure. The radiated power level for 32 pulsed elements was approximately 1 MPa. An imaging test shows that the system achieves axial and lateral resolutions of 40 microm and 0.2 mm, respectively. The entire scanning head dissipates approximately 1.6 W at a pulse repetition rate of 750 Hz.