Reflections on "Chrome Vinyls"

["S. Hieber" <shieber at yahoo_com>]

Chrome vinyl looks like interesting stuff for an aquatic environment.

http://www.signsupplystore.com/specialty_vinyls.asp

It might be useful as reflector material but it seems unlikely to be as
good as highly polished aluminum specular reflectors like AH Supply's. 
While the vinyl layer makes the "chrome vinyl" material appear glossy,
the reflective material, the aluminum foil within, doesn't appear to be
highly polished.  So there would be the same *kind* of diffusion (but
perhaps less of it) that you would get from typical aluminum foil (sans
creases).  Typical aluminum foil reflectivity is something less than
you can get with good coat of white paint.  The chrome vinyl might be
better than white paint and being vinyl, it's waterproof.

If the vinyl layer has any appreciable thickness that further reduces
the reflective efficiency.  AH Supply reflectors, or more specifically
Miro, has an extremely thin protective layer that is the rather highly
specular aluminum copmpound that makes it Miro hard to beat as an
effective and durable reflector material.

While the manufacturer's web site  (alanod.de) is down, you can find
out more about Miro here:

http://www.anomet.com/products.html

Shape is as important as the material.  If a light source is in the
focal point of a truly parabolic reflector,  all the light is relected
straight forward from the reflector (it's a questions of angles). 
Deviating from that placement or that reflector shape spreads the
light.  

It's described better here:

http://www.batesville.k12.in.us/Physics/PhyNet/Optics/Curved%20Mirrors/Reflection_Curved_Mirror.html

Scott H.

__________________________________________________
Do You Yahoo!?
Sign up for SBC Yahoo! Dial - First Month Free
http://sbc.yahoo.com