CaF2 Window

Calcium fluoride is often used in spectroscopic windows and lenses due to its high transmission from 250nm to 7μm. Its low absorption and high damage threshold makes it a popular choice for excimer laser optics. Calcium fluoride’s low index or refraction allows it to be used without an anti-reflective coating. The Knoop hardness of calcium fluoride is 158.3. TECHSPEC® Calcium Fluoride (CaF2) Windows manufactured from vacuum UV grade calcium fluoride are commonly found in cryogenically cooled thermal imaging systems.


1 ) Low Absorption, High Transmission UV Grade Calcium Fluoride

2 ) Ideal for Applications Ranging from 250nm – 7μm

3 ) Low Index of Refraction


1 ) Diameter: 3~375mm

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

0.13 to 10 micron

Refractive Index

1.39908 at 5 micron

Refractive Loss

5.4% at 5 micron

Crystal/Class Structure

Cubic CsCl, Pm3m

Cleavage Plane

No cleavage planes

Thermal Properties

Thermal Expansion

47.9×10-6 /℃ at 273K

Thermal Conductivity

9.71 W m-1K-1

Melting Point

1360 ℃

Specific Heat Capacity

854  J Kg-1K-1

Mechanical Properties


3.18 g/cc


158.3 (100) with 500g indenter

Youngs Modulus

75.8 GPa

Shear Modulus

33.77 GPa

Bulk  Modulus

82.71 GPa

Poisson Ratio


Elastic Limit

C11=164 C12=53 C44=33.7

Molecular Weight


Chemical Properties


0.0017 g/100g water at 20℃

Technical Images