Magnesium Fluoride


Magnesium Fluoride is commonly used for optical components in wide spectrum band from the vacuum ultraviolet to the infrared, since it is transparent over the entire range of wavelengths (from 0.11-0.12 µm to 7.5-8.0 µm).

Magnesium Fluoride combines wide spectral transmittance bandwidth birefringence phenomenon. Its birefringence makes polarizing optics for the ultraviolet region possible. With Lithium Fluoride, it is one of the two materials that will transmit in the vacuum ultraviolet range at the hydrogen Lyman-alpha line (121nm).

Magnesium Fluoride is tough and is used if extreme ruggedness and durability is required. It is resistant to thermal and mechanical shock. Irradiation doesn’t lead to color centers. The material is used for the production of windows, prisms, lenses and other optical items in the range from the vacuum ultraviolet to the infrared.

We use for our optics high quality crystals growth on the Czochralsky and Bridgman Methods and supply high transparency and low loss optical windows, prisms, lenses, achromatic lenses and other optical components. Magnesium Fluoride is sold in two qualities (monodomain and polydomain) and in three grades – IR, UV and VUV grade.
Optical Properties
Transmission range in µm @10% min. 0.12 - 9.6
Transmission range in µm @50% min. 0.12 - 8.5
Refractive index @ 633nm 1.375 (no)
1.389 (neo)
Reflection losses in % at 1 surface 2.52 @ 633nm
Reflection losses in % at 2 surfaces 11.2 @ 120nm
dn/dT in 1/K 2.3 · 10-6 (parallel c-axis)
1.7 · 10-6 (perpendicular c-axis)
Physical Properties
Density in g/cm³ 3.177
Melting point in °C 1255
Specific heat capacity in J/(kg · K) 1004
Thermal Conductivity in W/(m · K) 21 (parallel) @300K
33.6 (perpendicular) @300K
Thermal Expansion in 1/K 13.7 · 10-6 (parallel)
8.9 · 10-6 (perpendicular)
Dielectric constant 4.87 (parallel)
5.45 (perpendicular)
Solubility in water in g/100g 2 · 10-4 @ 0-60°C
Mohs hardness 6
Knoop hardness in kg/mm² 415
Material type Single crystal, synthetic
Crystal type tetragonal
Crystal structure tP6
Lattice constant in Å a = 4.0623
c = 3.053
Elastic coeficients in GPa C11 = 138
C12 = 88
C13 = 62
C33 = 301
C44 = 56.5
C66 = 95.5
Young's Modulus (E) in GPa 138.55
Shear Modulus (G) in GPa 54.66
Bulk Modulus (K) in GPa 101.32
Rupture Modulus in MPa 60
Apparent elastic limit in MPa 49.6
Poisson ratio 0.276
Spectral Properties