ATM Gilding

[Anthony Stillman <atmer@flash.net>]

All,

The reflectivity of evaporated gold hovers just below 40% from about 250nm
to about 500nm.  At 500 nm it rises sharply, leveling off at about 700nm.
>From 700nm to beyond 25um the reflectivity of gold is about 98%

The reflectivity of evapoated silver is about 30% at 220nm and drops to
about 3% just beyond 300nm.  From there is rises sharply to about 95% at
400nm then levels off around 700nm.  From 700nm to beyond 10um the the
reflectivity of silver is about 99%

The reflectivty of evaporated aluminum is about 95% at 225nm and drops to
83% at about 800nm.  From 800nm to 5um it rises to about 94% then levels
off and drops a percent or two from 5um to 25um.

The reflectivity of polished copper is about 40% at 220nm and drops to
about 35%  just short of 300nm.  From 300nm to 520nm the reflectivity rises
from 35% to about 70%.  From 520nm to 750nm it rises for about 70% to 90%.
The reflectivity continues to rise to about 98% at 6um then levels off and
drops a percent or two from 6um to 25um.

There are, of course, a number of techniques for coating surfaces with thin
metal films.  Each means produces a different reflectivity-wavelength
profile.  Further, overcoats, sub-surface materials, post application
processing  oxidation, exposure to the elements and any number of other
things also effect the reflectivity.

Anthony


Books I refered to:
"Handbook of Military Infrared Technology" Edited by William L. Wolfe
Library of Congress Catalog Card No. 65-62266
Office of Naval Research Department of the Navy 1965
(I think this time, mines older than yours Richard)

"Handbook of Optics" Edited by Walter G.Driscoll and William Vaughan
ISBN 0-07-047710-8  Mcgraw-Hill copyright 1978