> > thought experiment: If you were to mark on the surface of the sign   
   >   
   > > with a transparent marker, like a piece of parraffin, would it glow?   
   >   
   > > And more: If you were to mark with a white-board marker which leaves   
   >   
   > > little or no bulk material, just some dye, would it also glow?   
   >   
   > > Finally, it seems that roughing the surface also makes it glow. This   
   >   
   > > probably trivial scattering untelated to "evanescent."   
   >   
   > snip snip   
   >   
   > The guided light refracts normally into the binder of the marker ink,   
   >   
   > then scatters off the particles and other irregularities.   
   >   
   >   
   >   
   > hobbs at electrooptical dot net   
   >   
   > http://electrooptical.net   
      
   ========================   
   Phil, younoyice I couched my questio as an experiment, in the tradition of   
   Percy Bridgman in Physics heh heh   
   So - If I were to add a transparent 'bump' to a light pipe, then that will   
   cause light to come out.   
   This seems reasonable - It's just the same as shining a projector onto some   
   pigment particles in solution.   
   thanks   
   jb   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)