Page 268 - Modern Optical Engineering The Design of Optical Systems

248 Chapter Eleven

.3 .4 .5 .6 .7 .8 .9 1.0 1.5 2.0 4.0 8.0
100%
Ag
Al Al
90% Rh
Cu
Au
80%
70%
Rh Al ALUMINUM
REFLECTANCE 50% Ag Cu Au Au GOLD
60%

Ag
SILVER
40%
Cu
RHODIUM
Rh COPPER
30%
20%

10%

.3 .4 .5 .6 .7 .8 .9 1.0 1.5 2.0 4.0 8.0
WAVELENGTH in µm
Figure 11.6 Spectral reflectance for evaporated metal films on glass. Data represent
new coatings, under ideal conditions.

Figure 11.7 Spectral reflectance of aluminum mirrors. The solid curves are for alu-
minum films with various types of thin film overcoatings—either for protection or
for increased reflectivity. The dashed line is an extra-high-reflectance multilayer
coating. All coatings shown are commercially available.