On Sun, 07 Oct 2007 15:44:29 -0700, GoldIntermetallicEmbrittlement
g wrote:

On Sun, 07 Oct 2007 17:20:48 -0500, John Fields
wrote:

On Sun, 7 Oct 2007 15:14:03 -0500, "Lord Garth"
wrote:


"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!

---
OK...

Pretty cool stuff.

http://www.precitech.com/index.html

This is what our piezo stacks went into.

Tightest tolerances in the world.

---
Very nice. :-)

I was watching "How it's made" or "How do they do it" the other day,
and they were showing how contact lenses are made today. Absolutely
amazing! Any profile can be cut into the lens and the steps will be
undetectable.

That is, no jaggies will be seen by the patient...


--
JF