Coefficients of Expansion and Densities of Optical Materials
Material
Coefficient of Expansion(×10-6 per °C)
Density (lbs/cubic in.)
Aluminum
23.8
0.10
Brass (cast)
18.8
0.30
Carbon (diamond)
1.2
0.25
Carbon (graphite)
7.9
-
Copper
16.2
0.32
Germanium
5.9
0.20
Glass (optical)
maximum
15.0
0.22
minimum
4.0
0.08
average
8.0
0.11
Gold
14.0
0.70
Invar (36% Ni)
0.9
0.30
Iron (cast)
10.0
0.27
Iron steel
13.2
0.28
Lead
28.0
0.41
Magnesium (cast)
27.0
0.06
Nickel
12.6
0.32
Plastics (optical)
65.0
0.04
Platinum
9.0
0.77
Pyrex
3.5
0.10
Quartz, fused
0.6
0.08
Rubber (hard)
80.0
0.04
Silicon
2.33
0.08
Steel, stainless
12.0
0.30
Zinc sulfide (ZnS)
7.9
0.15
Zinc selenide (ZnSe)
7.6
0.20
Source: Walker Associates
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