MgF2

Magnesium Fluoride (MgF2 crystal) is used for optical elements where extreme ruggedness and durability is required. Its useful transmission range is 0.11 µm - 8.5 µm. Irradiation does not lead to color centers. It is a rugged, hard material which is resistant to thermal and mechanical shock and can be worked to the highest standards. Considerable mechanical shock is needed to cause cleavage which is near perfect when it occurs. MgF2 single crystals is a positive crystal and slightly birefringent and usually supplied with the optic axis cut perpendicular to the window faces.

Magnesium Fluoride (MgF2 crystal) has the following exceptional properties that make it a very important optics crystal:
(1) High optical transmittance from the vacuum ultraviolet to the infrared spectrum region(0.11~8.5µm).
(2) Resistant to mechanical and thermal shock, to radiation.
(3) Chemically stable.
(4) Used for Optical prisms, lenses, wedges, windows, other optical components,and etc.
(5) A positive birefringent crystal, used for optical fiber communication.

Physical and Optical Properties

Crystal Type : Tetragonal, P42/mnm a=4.64 Å, c=3.06 Å
Density : 3.16 g/cm3
Melting Point : 1255 deg. C
Boiling point : 2239 deg. C
Thermal Conductivity : 3.15W/m K
Specific Heat : 920 J/(kg K)
Thermal Expansion : //C 9x10^-6; ⊥C 14x10^-6/ K
Hardness (Knoop) : 415,576 kg/mm^2
Hardness (Mho) : 5--6
Young’s Modulus : 138.5 GPa
Elastic Coefficient : C11=140 C12=89 C44=57 C13=63 C66=96
Dielectric Constant : 105 ~107 Hz 5.45
Solubility in Water : 0.0076 g / 100 g, 18deg. C
Absorption Coefficient : 0.07 at 0.2µm,0.02 at 5.0µm
Transmission Range : 0.11 - 8.5
Fluorescence : Weak yellow upon excitation at 590 nm
Temperature coefficient of refractive index: dno/dT = 2.3 x 10^-6 @ 497.4 nm

Refractive Index

General Specifications

Material: DUV grade MgF2
Transmittance: 50% @ 120nm, 60% @ 140nm, 90% @ 200nm,93% @ 300-5000nm.
Diameter Tolerance : +0.0/-0.10mm
Thickness Tolerance : +0/- 0.10mm
Clear Aperture : >Central 90% of diameter
Surface Quality : 20 - 10
Parallelism : <1 arc min
Surface Flatness : per 25mm λ/10
Chamfer 0.15~0.35mm x 45°

OptoCity offer MgF2 single crystal with high transmittance in DUV for large single domain size, and especially suitable for Excimer or DUV windows.

We can produce UV Blank, UV Windows, UV Lenses, UV Cylindrical Lenses, UV Prisms, UV Wedges according to custmers' requirments and drawings.