On the other hand, if the light is invisible but the beam is not,
we're talking about even MORE energy. I've never heard of a
laser sufficiently powerful to produce a visible ionisation path
slong the collimated beam. (With convergence focussing, yes.)
But they're probably out there..
-- #ken P-)}Ken Coar <http://Web.Golux.Com/coar/> Apache Software Foundation <http://www.apache.org/> "Apache Server for Dummies" <http://Apache-Server.Com/>