Beam Predictability for high power transducers
Focus control is an important element in designing
a transducer for medical therapy: it is essential to accurately
control the treatment zone and to thus protect the healthy tissue.
The intrinsic features of Imasonic's piezo-composite
structure enable radial modes to be reduced, thus favoring the vibration
according to the thickness mode. The electro-acoustic response obtained
is thus very close to the theory and the acoustic field does not
present any hot points outside the focal point. See the illustration
Cathignol et al., Comparison of acoustical fields
radiated from piezoceramic and piezocomposite highly focused transducers,
J. Acoust. Society of America 1999
Simulated radiated field
The figures below show clearly the limitations of
PZT transducers through the possible generation of unexpected hot
spots that may cause unexpected and uncontrolled lesions in tissues.
This phenomeneon is mainly due to the generation of lamb waves inside
the PZT plate.
Experimental radiated field, showing spurious hot spots
The figure below shows the very good beam predictability
with piezocomposite transducers
Experimental radiated field, very close to the simulation