BaF2 Window

Barium Fluoride (BaF2) Windows can be used in a variety of applications, such as infrared spectroscopy, due to their wide broadband transmission that extends from the deep ultraviolet to the long-wave infrared. Barium fluoride’s low index of refraction of 1.48 provides high transmission without the need for anti-reflection coatings. Barium fluoride windows can be used up to 800°C in a dry environment, but prolonged exposure to moisture can degrade transmission in the vacuum ultraviolet range. While barium fluoride windows are less resistant to water than calcium fluoride, BaF2 windows are the most resistant optical fluoride to high-energy radiation, but feature lower UV transmittance. BaF2 has a Knoop hardness of 82.


1 ) Excellent Transmission from 200nm – 12μm

2 ) Resistant to High-Energy Radiation

3 ) Provide High Transmission without AR Coatings


1 ) Diameter: 3~200mm

2 ) Diameter Tolerance: +/-0.2mm

3 ) Thickness Tolerance: +/-0.03mm

4 ) Aperture: >90%

5 ) Surface Quality: 80/50~10/5 (S/D)

6 ) Parallelism: <1 arc minute

7 ) Chamfer: 0.3-0.5mmx45°

Optical Properties

Transmission Range

0.15 to 12 micron

Refractive Index

1.45 at 5 micron

Refractive Loss

6.5% at 5 micron

Crystal/Class Structure

Cubic CaF2

Cleavage Plane

(111), Perfect

Thermal Properties

Thermal Expansion

18.1×10-6/℃ at 273K

Thermal Conductivity

11.72 W m-1K-1 at 286K

Melting Point

1386 ℃

Specific Heat Capacity

410 J Kg-1K-1

Mechanical Properties


4.89 g/cc


Knoop 82 with 500g indenter

Youngs Modulus

53.07 GPa

Shear Modulus

25.4 GPa

Bulk Modulus

56.4 GPa

Poisson Ratio


Elastic Limit

26.9 Mpa (300psi)

Molecular Weight


Chemical Properties


0.17g/100g water at 23℃

Technical Images