Material CAF2
Calcium Fluoride is used for optical windows, lenses and prisms in the 0.15 μm - 9 μm (ultraviolet to infrared) regions. The low power absorption has made this material attached to wide use in high power laser optics. Polished surfaces are stable and will last several years under normal conditions. Due to its composition, CaF2 has a much longer usable lifetime than most materials operating in fluorine environments.
Calcium Fluoride, which is grown by vacuum Stockbarger technique, has a low refractive index, hence can be used without anti-reflection coating. Material for IR use is grown using naturally mined fluorite, in large quantities at relatively low cost. Maximum available size: 380 mm Dia x 70 mm Thk.
Calcium Fluoride (CaF2)
BASE PROPERTIES
PARAMETER
VALUE
OPTICAL
Transmission Range
0.13 to 10 microns
Refractive Index
1.39908 at 5 microns
Reflection Loss
5.4% at 5 microns (2 surfaces)
Restrahlen Peak
35 microns
dN/dT
-10.6 x 10-6e/°C
PHYSICAL
Density
3.18 g/cm3
Melting Point
1360 °C
Thermal Conductivity
9.71 W/(m*K)
Thermal Expansion
18.85 x 10-6e/°C
Hardness
Knoop 158.3 kg/mm2 (100)
Specific Heat Capacity
854J/(kg K)
Dielectric Constant
6.76 at 1MHz
Young's Modulus (E)
75.8 GPa
Bulk Modulus (K))
82.71 GPa
Elastic Coefficients
C11=164 MPa, C12=53 MPa, C44=33.7 MPa
Apparent Elastic Limit
36.54 MPa
Poisson Ratio
0.26
CHEMICAL
Solubility
0.0017g/100g water at 20 °C
Molecular Weight
78.08
Class/Structure
Cubic (111) cleavage
REFRACTIVE INDEX
| Wavelength, μm | 0.19 | 0.21 | 0.25 | 0.33 | 0.41 | 0.88 |
|---|---|---|---|---|---|---|
| Refractive Index | 1.51 | 1.49 | 1.47 | 1.45 | 1.44 | 1.43 |
| Wavelength, μm | 2.65 | 3.90 | 5.00 | 6.20 | 7.00 | 8.22 |
|---|---|---|---|---|---|---|
| Refractive Index | 1.42 | 1.41 | 1.40 | 1.38 | 1.36 | 1.34 |
