🚀 go-pugleaf

Jon J Thaler says:
>I would suppose that a photocopier uses the diffuse reflection from
>the document to be copied.  Paper does not have much specular
>reflection (and that which it does have is not from the ink - try reading
>a glossy magazine when the reflected light shines in your eyes).
> 
>Your mirror, having *ONLY* specular reflection, is as invisible to the
>copier as the glass plate you put the paper on.
 

Actually, I think the problem is one of where the lens focuses.  Think
of it this way:
Say the light source of the photocopier is x inches below the glass.  
You could remove the mirror and put the same kind of light source x
inches above the glass (some copiers have a "flash", others a strip of
white or green light which scans across the glass) and achieve roughly
the same conditions.  The point is, that would result in a black copy
too.  Why?  I think it's because the lens focuses on the glass, and not
a distance x inches above the glass.  That's why you get a black copy
if you open the copier lid and make a copy without placing anything on
the glass.  Even if there are strong overhead lights above the copier,
that light doesn't cause the copy to come out white.

                            - Simon