Borosilicate Glass, BK7

BK7 is one of the most common borosilicate crown glass with high homogeneity and low bubble content. BK7 is an excellent all-around material widely used in visible and NIR windows, lenses, and prisms.

Refractive Index, n: 1.51872 @ 546.1 nm
Transmission Range: 0.35 – 2.0 µ
Thermal expansion coeff: 8.3 x 106 / ℃ at 0-200 ℃
Density: 2.51 g/cm3

UV Grade Fused Silica (SiO2)

UV grade Fused Silica is synthetic amorphous silicon dioxide of extremely high purity. Properties include high UV transmission, low thermal expansion coefficient, and high damage threshold.

Refractive Index, n: 1.50855 @ 250.0 nm
Transmission Range: 0.18 – 3.5 µ
Thermal expansion coeff: 5.5 x 107 / ℃ at 0-200 ℃
Density: 2.20 g/cm3

Calcium Fluoride (CaF2)

Calcium Fluoride is a cubic signal crystal material grown using the vacuum Stockbarger technique with good vacuum UV to infrared transmission. Care must be used when thermally cycling CaF2.

Refractive Index, n: 1.4349 @ 546.1 nm
Transmission Range: 0.15 – 9.0 µ
Thermal expansion coeff: 1.75 x 105 / ℃ at -60-60 ℃
Density: 3.18 g/cm3

Magnesium Fluoride (MgF2)

Magnesium Fluoride is a positive birefringent crystal grown using the vacuum Stockbarger technique with good vacuum UV to IR transmission. MgF2 is resistant to thermal and mechanical shock.

Refractive Index, n: 1.4231/ 1.4367 @ 200.0 nm
Transmission Range: 0.13 – 7.0 µ
Thermal expansion coeff: 1.0 x 105 / ℃ at -60-60 ℃
Density: 3.177 g/cm3

Crystal Quartz

Crystal Quartz is a positive uniaxial birefringent signal crystal grown using a hydrothermal process. Due to its birefringent nature, crystal quartz is most commonly used for waveplates.

Refractive Index, n: 1.54617/ 1.55535 @ 546.1 nm
Transmission Range: 0.16 – 2.5 µ
Thermal expansion coeff: / ℃ (Ⅱ), 7.1 x 106 ℃ (≤)
Density: 2.649 g/cm3

Silicon (Si)

Silicon is used as mirror substrate for lasers because of its thermal conductivity, lightweight, and hardness. Due to the strong absorption at 9.0µ m, Silicon is widely used for CO2 mirrors.

Refractive Index, n: 3.436 @ 3.0
Transmission Range: 1.2 – 8.0 µ
Thermal expansion coeff: 2.55 x 106 / ℃ at 20 ℃
Density: 2.329 g/cm3

Germanium (Ge)

Germanium is used widely for lenses and windows in infrared laser systems. Germanium is the hotter it gets the more the absorption increases. At 200Â℃ it becomes non-transmissive.

Refractive Index, n: 4.0406 @ 6.0µ
Transmission Range: 2.0 – 17.0 µ
Thermal expansion coeff: 5.5 x 106 / ℃ at -60-600 ℃
Density: 5.33 g/cm3

Zinc Selenide (ZnSe)

Zinc Selenide has a very low absorption coefficient and is used extensively for high power infrared laser optics. Zing Selenide is a relatively soft material and scratched rather easily.

Refractive Index, n: 2.4028 @ 10.6µ
Transmission Range: 0.63 – 18.0 µ
Thermal expansion coeff: 7.57 x 106 / ℃ at 20 ℃
Density: 5.27 g/cm3

Zinc Sulfide (ZnS)

Zinc Sulfide is used in harsh environments as it is harder and more resistant to scratching. It can be used for infrared windows in high-speed aircraft and vacuum applications.

Refractive Index, n: 2.201 @ 10.6µ
Transmission Range: 0.4 – 14.0 µ
Thermal expansion coeff: 6.5 x 106 / ℃
Density: 4.09 g/cm3