Table 1. Basic properties of several of the most ubiquitous optical materials.
Material Transmission Range Refraction Index Range Reflection Loss Thermal Expansion
Coefficient
Density (g/cm3) (kg/mm2)
BAK1 280 nm to 2.5 µm 1.545 to 1.613 <2% @ 365 nm to1.53 µm 8.6 x10-6/K @ 300 K 3.19 530
Barium
fluoride
(BaF2)
150 nm to 12 µ 1.41 to 1.82 6.5% @ 5 µm(1.45 @ 5 µm) 18.1 x10-6/°C @ 273 K 4.893 82
BK7 350 nm to 2.5 µm 1.513 to 1.536
(1.517 @ ~587 nm)
8.1% @ ~587 nm 7.1 x 10-6/ K 2.51 610
Calcium
fluoride
(CaF )
130 nm to 10 µm 1.31 to 1.58
(1.399 @ 5 µm)
5.4% @ 5 µm 18.85 x 10-6/ °C 3.18 158.3
Cadmium
telluride
(CdTe)
850 nm to 20 µm 2.57 to 2.88
(2.653 @ 10 µm)
32% @ 10 µm 5.9 x 10-6/ K @ 293 K 6.2 45
Cesium
bromide
(CsBr)
250 nm to 40 µm 1.56 to 1.71 11.6% @ 11 µm 47.9 x 10-6/ °C @ 273 K 4.44 19.5
Crystal
quartz
(SiO2)
180 nm to 3.5 µm; >40 µm 1.521 to 1.661 8.8% @ 600 nm 7.1 x 10-6 to 13.2 x10-6/ °C 2.649 741
Fused-silica
(SiO2)
180 nm to 2.2 µm 1.41 to 1.55
(1.47 @ 4 µm)
7% @ 400 nm 0.55 x 10-6/ °C @ 300 K 2.203 500
Gallium
arsenide
(GaAs)
0.9 to 16 µm 3.19 to 3.49
(3.2727 @ 10.33 µm)
44% @ 10.33 µm 5.7 x 10-6/ °C @ 300 K 5.315 750
Germanium
(Ge)
1.8 to 23 µm 4.0021 to 4.1020
(4.0026 @ 11 µm)
53% @ 11 µm 6.1 x 10-6/ °C @ 298 K 5.33 780
Lithium
fluoride
(LiF)
120 nm to 6 µm 1.30 to 1.91
(1.392 @ 600 nm)
5.2% @ 600 nm 37 x 10-6/ K @ 283 K 2.639 102
Magnesium fluoride
(MgF2)
120 nm to 7 µm 1.31 to 1.78
(1.413 @ 220 nm)
5.7% @ 220 nm 8.9 x10-6 to 13.7 x10/ K 3.18 415
Potassium
bromide
(KBr)
230 nm to 25 µm 1.425 to 1.589
(1.527 @ 10 µm)
8.3% @ 10 µm 43 x 10-6/ K @ 300 K 2.753 7
Pyrex 290 nm to 2.8 µm 1.473 @ 589 nm 10% @ 340 nm to 2.2 µm 3.3 x 10-6/ °C 2.23 481
Sapphire
(Al2O3)
170 nm to 5.5 µm 1.607 to 1.929
(1.754 @ 1.06 µm)
14% @ 1.06 µm 5.0 x 10-6 to 5.6 x10-6/ K 3.97 2000
Silicon
(Si)
1.2 to 15 µm 3.417 to 3.497
(3.422 @ 5 µm)
46.2% @ 5 µm 2.6 x 10-6/ °C @ 20 °C 2.33 1150
Titanium
oxide
(TiO2)
430 nm to 5 µm 2.24 to 2.853
(2.555 @ 690 nm)
30% @ 2 µm 7.1 x 10-6 to 9.2 x 10-6/ °C 4.26 879
Zerodur 400 nm to 2.5 µm 1.513 to 1.559
(1.542 @ 587.6 nm)
4.6% @ 587.6 nm 0.2 x 10-6 to 0.10 x10-6/ K 2.53 620
Zinc
selenide
(ZnSe)
600 nm to 21 µm 2.327 to 2.675
(2.403 @ 10.6 µm)
29.1% @ 10.6 µm 7.1 x 10-6/ °C @ 273 K 5.27 120
Zinc
sulfide
(ZnS)
1 to 13 µm 1.998 to 2.516
(2.192 @ 10.6 µm)
24.6% @ 10.6 µm 6.6 x 10-6/ °C @ 273 K 4.08 160