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CaF2 - Calcium Fluoride

Calcium Fluoride (CaF2), a cubic single-crystal materal, has widespread applications in the ultraviolet and infrared spectra. CaF2 is an ideal material for use with excimer lasers. It can be manufactured into windows, lenses, prisms, and morror substrates.

CaF2 transmits over the spectral range of about 130nm to 10nm as shown in the chart.

Traditionally, it has been used primarily in the infrared rather than in the ultraviolet.CaF2 occurs naturally and can be mined. It is also produced synthetically using the time-and-energy-consuming Stockbarger method.

Unfortunately, achieving acceptable deep ultraviolet transmission and damage resistance in FaF2 requires much greater material purity than in the infrared and it completely eliminates the possibility of using mined material.

To meet the need for improved component lifetime and transmission at 193 nm and below, manufacturers have introduced a variety of inspection and processing methods to identify and remove various impurities at all stages of the production process. The needs for improved material homogeneity and stress birefringence have also caused producers to make alterations to the traditional Stockbarger approach. These changes allow tighter temperature control during crystal growth, as well as better regulation of vacuum and annealing process parameters.

Excimer-grade CaF2 provides the combination of deep ultraviolet transmission (down to 157 nm), high damage threshold, resistance to color-center formation, low fluorescence, high homogeneity, and low stress-birefringence characteristics required for the most demanding deep ultraviolet applications.

znsms spec chart image
Dispersion Constants
B1
0.5675888
B2
0.4710914
B3
3.8484723
C1
0.00252643
C2
0.01007833
C3
1200.5560
Calcium Fluoride Constants
Density
3.18 g/cm3@25°C
Young's Modulus
1.75X107psi
Poisson's Ratio
0.26
Thermal coefficient of Refraction
dnldT=-10.6X10-6/°C
Coefficient of Thermal Expansion
18.9 X10-6/°C (20°-60°C)
Melting Point
1360°C
Refractive Index
Wavelength µm
Index of Refraction
 
Wavelength µm
Index of Refraction
 
0.193
1.501
 
1.0
1.428
0.248
1.468
 
1.5
1.426
0.257
1.465
 
2.0
1.423
0.266
1.462
 
2.5
1.421
0.308
1.453
 
3.0
1.417
0.355
1.446
 
4.0
1.409
0.486
1.437
 
5.0
1.398
0.587
1.433
 
6.0
1.385
0.65
1.432
 
7.0
1.369
0.7
1.431
 
8.0
1.349