Transmit pulse

In order to use the L11-4v probe as a λ-pitch array the transmit frequency should be around 5.13 MHz. The closest frequency allowed by the Verasonics Vantage system is 5.208 MHz, which is chosen as transmit frequency. The following parameters define the pulse

Transmit frequency 5.208 MHz
Sampling frequency 20.832 MHz
Pulse bandwidth 67%
Transmit voltage 30 V
Excitation 2.5 cycles

 

The pulse waveform was studied in a water tank by transmitting a single plane wave with 0° tilt. The acoustic pressure was measured on the beam axis at the depth z = 14.5 mm, i.e. the depth of maximum attenuated pulse intensity integral. An attenuated peak rarefactional pressure of 1.57 MPa was observed, corresponding to MI=0.79. The pulse waveform is show below

 

A power scan was performed at the depth z =22.7 mm, corresponding to the breakpoint distance, and the following acoustic measurements were obtained:

Voltage 30 V
Depth 22.77 mm
Acoustic Power 3.24e-2 · PRF mW
Bounded power (1 cm) 8.02e-3 · PRF mW
TIS (non-scanning) 3.57e-4 · PRF
TIS (scanning) 1.94e-4 · PRF
TIB (non-scanning) 7.10e-4 · PRF
TIB (scanning) 1.94e-4 · PRF
TIC 5.42e-4 · PRF