You wrote;
> a suggestion of using a "Laser Beam Listening Device" and a Laser
> transmitter source which is modulateable!
Intriguing....I'd forgotten about a PBS special many years ago where they
used a laser to reflect off a block of steel about a 1/2 mile away..
In the video, they used a telescope coupled to a video camera to get a
clear closeup of what happened..
The beam was modulated with various frequencies and the reflected signal
was detected, when the output signal was reflected back at the same
intensity, that frequency was locked in and intensified.....a hole was
blown right through the middle of that steel slightly larger than the
beam....it was an incredible video and I don't recall the name of it.
Makes for all kinds of interesting weapons, thats for sure, but as you
say, Dave, it could be used to find the mass resonance in a non-contact
way, thus not skewing the natural frequency.....good idea!!
-- Jerry W. Decker / jdecker@keelynet.com http://keelynet.com / "From an Art to a Science" Voice : (214) 324-8741 / FAX : (214) 324-8741 KeelyNet - PO BOX 870716 - Mesquite - Republic of Texas - 75187