Window crystals

/MgF2 crystal Magnesium Fluoride

MgF2 crystal Magnesium Fluoride

MgF2 or Magnesium Fluoride is positive uni-axial crystal with a very high optical transmittance from the vacuum UV to IR. It is regularly used for optical elements where extreme ruggedness and durability is required. It also has a large resistance to mechanical and thermal shock, to optical radiation, and is chemically stable, making it a very useful materials for UV and IR optics.

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  • Shipping Port:

    Fuzhou, China
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MgF2 or Magnesium Fluoride is positive uni-axial crystal with a very high optical transmittance from the vacuum UV to IR. It is regularly used for optical elements where extreme ruggedness and durability is required.

Main application:

1) VUV , UV ,IR optical systems

2) UV photomultiplier tubes

3) Excimer lasers

4) Optical fiber communications industry


1) High optical transmittance from the vacuum ultraviolet to the infrared spectrum region(0.12~8.5μm).

2) Resistance to mechanical , thermal shock and radiation

3) Chemically stable

4) A positive birefringent crystal

5) Used for Optical prisms, lenses, wedges, windows, other optical components etc

Basic properties of MgF2 crystal:

Chemical Formula



3.18 g/cm3

Melting Point


Boiling Point


Molar Mass


Thermal Conductivity

3.15W/m K

Specific Heat

920 J/(kg K)

Thermal Expansion Coefficient

C 9×10–6C 14 ×10–6 / K

Knoop Hardness

415,576 kg/mm2

Mohs Hardness


Young's Modulus

138.5 GPa

Shear Modulus

54.66 GPa

Bulk Modulus

101.32 GPa

Rupture Modulus

49.6 MPa

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, 18

Lattice Parameter

a=4.64 Å, c=3.06 Å

Crystal Type

Tetragonal, P42/mnm

Cleavage Planes

(100), (110)

Absorption Coefficient

0.07 at 0.2µm,0.02 at 5.0µm

Poisson's Ratio


Transmission Range

0.11 - 8.5

Vapor Pressure

1 Pa(at 1150), 10 Pa(at 1300)


IR, UV , DUV and VUV


Weak yellow upon excitation at 590 nm

HGO offers MgF2 specifications:


a-cut or <100> ;C-cut or<001>; random (-RM) or as specified

Wavefront Distortion:

λ/6 per inch @ 632.8 nm

Dimension Tolerances

rods with diameter: +0.0/-0.05 mm , Length: ±0.1 mm

Surface Quality:

20/10 Scratch/Dig MIL-O-1380A


< 20


< 10

Clear Aperture:

> 85%

Surface Flatness:

< λ/6 @ 632.8 nm


< 0.25 mm @ 45deg.


Upon customer request


Uncoated or upon customer’s request

Quality Warranty Period

One year under proper use

Why Choose HGO ?

HG OPTRONICS.,INC. has the ability to supply high quality MgF2 Magnesium Fluoride Crystal in mass production quantity. Material from HGO features with high transmittance in VUV(>70%) and UV wavelength ranges. Standard size for VUV windows are Dia.8 and Dia.6 with 1mm thickness.

HGO offer both a-cut (or [100] cut) MgF2 windows for the maximum birefringence and c-cut (or cut along the optical axis) with the minimum birefringence. Random-cut (cut along a random axis) MgF2 windows are also available. The thickness can be made as thin as 0.1mm. In addition, we can also produce other types of window crystals like YAG crystals, BaF2,LiF Crystals, etc.

HGO has a mass-production line for MgF2 crystals and have wide experiences and strong ability to supply such crystals with large quantity and in very short delivery time.

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