Specifications:
| Materials | IR grade Calcium fluoride crystals | Aperture | >90% |
| Dimension Tolerance | +0.0/-0.2mm | Thickness Tolerance | +/-0.1mm |
| 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 | 0.13 to 10 μm | Refractive Index | 1.39908 at 5 μm (1) (2) |
| Reflection Loss | 5.4% at 5 μm | Absorption Coefficient | 7.8 x 10-4 cm-1 @ 2.7 μm |
| Reststrahlen Peak | 35 μm | dn/dT | -10.6 x 10-6 /°C (3) |
| dn/dμ = 0 | 1.7 μm | Density | 3.18 g/cc |
| Melting Point | 1360°C | Thermal Conductivity | 9.71 W m-1 K-1 (4) |
| Thermal Expansion | 18.85 x 10-6 /°C (5)(6) | Hardness | Knoop 158.3 (100) with 500g indenter |
| Specific Heat Capacity | 854 J Kg-1 K-1 | Dielectric Constant | 6.76 at 1MHz (7) |
| Youngs Modulus (E) | 75.8 GPa (7) | Shear Modulus (G) | 33.77 GPa (7) |
| Bulk Modulus (K) | 82.71 GPa (7) | Elastic Coefficients | C11 = 164 C12 = 53 C44 = 33.7 (7) |
| Apparent Elastic Limit | 36.54 MPa | Poisson Ratio | 0.26 |
| Solubility | 0.0017g/100g water at 20°C | Molecular Weight | 78.08 |
| Class/Structure | Cubic (111) cleavage |
Due to its high average transmission and low chromatic aberration relative to other IR materials, calcium fluoride(CaF2 ) is an excellent choice for windows and lenses for spectroscopy applications in the deep UV to near IR wavelength range (180 nm-8 µm). For its good transmission properties at LWIR range, the CaF2 are often selected as the windows for thermal imaging security inspections in electric power facilities and petroleum industries. A protective coated could be made on the windows surface to improve its deliquescence properties.
Hangzhou Shalom EO provides the crystals optical windows and also the windows assembly with metal holders for thermal imagine inspection applications.
Curves:
Transmission curve of the CaF2 windows of different thickenss
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