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Barium Fluoride (BaF2) Windows

  • Maximum diameter 200mm
  • Transmission range 0.2-11.0μm
  • Excellent as viewport windows and for IR spectroscope 
  • Coating Options: Protective Coating
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Materials IR Grade Barium fluoride Crystals Diameter Range ~ 200mm
Aperture >90% Dimension Tolerance +0.0/-0.1mm
Thickness Tolerance +/-0.2mm Surface Quality 60/40 S/D
Parallelism 1 arc minute Chamfer 0.3-0.5mmx45degree
Coating Optional protective coating

Physical and Optical Properties:

Transmission Range 0.15 to 12 μm Refractive Index 1.45 at 5 μm (1)
Reflection Loss 6.5% at 5 μm (2 surfaces) Absorption Coefficient 3.2 x 10-4cm-1 @ 6 μm
Reststrahlen Peak 47 μm dn/dT -15.2 x 10-6 °C (2)
dn/dμ = 0 1.95 μm Density 4.89 g/cc
Melting Point 1386°C Thermal Conductivity 11.72 W m-1 K-1 @ 286 K
Thermal Expansion 18.1 x 10-6 /°C @ 273 K Hardness Knoop 82 with 500g indenter (4)
Specific Heat Capacity 410 J Kg-1 K-1 (3) Dielectric Constant 7.33 at 1 MHz
Youngs Modulus (E) 53.07 GPa (3) Shear Modulus (G) 25.4 GPa (3)
Bulk Modulus (K) 56.4 GPa Elastic Coefficients C11 = 89.2 C12 = 40.0 C44 = 25.4 (2)
Apparent Elastic Limit 26.9 MPa (300psi) (4) Poisson Ratio 0.343
Solubility 0.17g/100g water at 23°C Molecular Weight 175.36
Class/Structure Cubic CaF2, Fm3m, (111) , cleavage

Barium Fluoride Windows, with their extremely broad transmission range from the deep UV to LWIR spectrum, are prevalent for Infrared applications requiring additional transmission in the Ultraviolet region. Barium Fluoride windows are excellent when being used for IR spectroscope and as viewport windows for thermal imaging inspection in electric power facilities and petroleum industries. A low refractive index of 1.48 implies BaF2 windows have high transmission rates without anti-reflection coating.

BaF2 has similar properties to CaF2, the difference mainly lies in that barium fluoride is more resistant to highly energetic radiation, and with an equivalent thickness, the transmission range of BaF2 extends approximately 1 micron further into the long-wave IR region than calcium fluoride. BaF2 could also accommodate high-temperature environments up to 800 ℃. However, exposure to moisture will increase its sensitivity to temperature and reduce its transmission rate to UV lights.

Hangzhou Shalom EO offers BaF2 Windows with protective coatings and assembled windows with metal holders. It is worth noting that BaF2 is a toxic material, so wear gloves during the handing process. You might also contact us to obtain detailed instructions.

Transmission curve of the BaF2 windows of different thickness

IR Inspection Windows Assemblies

IR Inspection Windows Assemblies

  • Anodized Aluminium holder
  • Dust tight design IP67
  • Variety IR materials: Germanium, CaF2 and BaF2
  • Easy installation, no screw needed