It is just a function of absorption at the laser wavelength, melting point,
heat conductivity, film strength (some measure of how solid the material is)
and a few other minor contributors. A "dark" surface at the laser
wavelength will efficiently absorb the light, converting it to heat, which
will then either dissipate into the bulk if the conductivity is good, or
raise the surface temperature high enough fast enough to melt or at least
weaken the bond to the subsurface plus expand the surface causing the
surface layer to spall off if the conductivity and heat capacity are low
enough. If there is a layer of dark dirt on top of shiny metal that
reflects well at the laser wavelength the dirt gets blasted off while the
metal is just warmed up a little but not damaged. Focus the laser into a
small spot and the metal will also get drilled into - notice the "spot" is a
strip that looks like maybe 1/16" wide by maybe 2"? That keeps the peak
power below the damage threshold for metals, I'm guessing. What they don't
show in that video is the laser itself, a cart maybe 3' x 3' x 4' from the
pics on their website, and while I'm not up on the latest efficiencies to
get a kw average power out of a NdYAG laser is going to take at least 10 kw
if not 20 kw from the wall plug. That's 91 amps of single phase 220 V,
similar to a 200-300 amp welder (so 3 phase and higher voltage would be
better). I just wish they had a price on the website.

-----
Regards,
Carl Ijames

"Ignoramus23944" wrote in message
...

On 2014-02-01, Larry Jaques wrote:

http://tinyurl.com/n83bc5q

ME WANT!


Looks great. I keep wondering how it works exactly, why does it remove
paint and dirt, but not underlaying material.