"John Fields" wrote in message
...

snip


Years ago, for the U.S. Navy, I designed and built a 40kHz projector
using a hollow spherical segment of PZT8 as the projector and a
couple of ENI 1kW power amps to drive it, underwater.

When we fired it up a visible, golf-ball sized area of cavitation
appeared at what was the focal point, the center of the sphere.

Pretty neat machine. :-)

I'll post pictures if anyone's interested.



Please do!