>An alloy of berrylium and aluminium is used to coat telescope mirrors, but
>when they want the best possible coating, silver is used since it has the
>largest albido of any known substance (i.e. ratio of reflected light to
>incident light). The mirrors are then quartz overcoated to prevent oxidation.
>I think the crinkled aluminum foil generated lots of little hot spots which
>acted like a bank of point sources which resulted in multiple imaging on
>the print.
What Bob says is true. When I was at Spectrolab we used similar materials to
coat nickel collectors and then overcoated again with quartz. I think that
coating a telescope mirror with flat white paint would lead to serious image
degradation.
Dick S.
Bostick & Sullivan
1541 Center Dr.
Santa Fe, New Mexico
87505