On Apr 21, 10:10*am, Helpful person wrote:
On Apr 20, 7:48*pm, RichD wrote:
Acoustic imagery is exactly analogous to light imagery except that
having longitudinal waves there is no polarization affect.
The long wavelength makes diffraction much more dominant that for
light. *Materials also have much greater dispersion over audible
frequencies.
Lenses tend to be difficult to demonstrate compared to mirrors due to
the large impedance mismatch to air. *However, for a very limited
bandwidth an interested demonstrator could easily be made using layers
of less dense materials to build up an anti reflection coating. *This
should not be too difficult due to the long wavelengths involved.
This is a demonstration I've always wanted to make but never had the
time.
http://richardfisher.com/
This thread has got me interested again about acoustic lenses. Does
anyone here have a source for speed and dispersion of sound in common
materials? It seems to me that liquids (and metals) are of most
interest as neither are very lossy. (Hardwood may also be a cool
material to use.)
By the way, the intensity (or volume) of imaged sound is solely
dependent on the NA, just as in light.
http://richardfisher.com/