CaF2
CaF2 is a crystal, which has good transmission from 170nm to 7800nm. It's slightly soluble in water and susceptible to thermal shock. CaF2 is commonly in IR components such as windows,Lenses and prisms.
Transmission Range: 170nm-7800nm
Thermal Expansion Coefficient: 18.85*10-6/K
Density: 3.18g/cm³
Sapphire
Sapphire is a single crystal aluminum oxide(AL2O3). It is one of the hardest materials. Sapphire has good transmission characteristics over the visible,and near IR spectrum.It exhibits high mechanical strength, chemical resistance, thermal conductivity and thermal stability.It is often used as window material in specific field such as space technology where scratch or high temperature resistance is required.
Physical Properties
| Crystal Symmetry Hexagonal | System |
| Lattice Constant | a=4.75;c=12.97 |
| Transparence Range | 0.18-4.5um |
| Density | 3.98g/cm³ |
| Mohs Hardness | 9 |
| Melting Point | 2030℃ |
| Thermal Conductivity | 0.04W/m/k |
| Expansion Coefficient | 8.4*10-6/k |
| Refractive Index | 1.755 |
Silicon(si) Crystals
Silicon(Si) is commonly used as a substrate material for infrared reflectors and windows in the 1.5um-8um region.The strong absorption band at 9um makes it unsuitable for CO2 laser transmission applications but it is frequently used for laser mirrors because of its high thermal conductivity and low density.Silicon is also a useful transmitter in 20um range.
Physical Properties
| Material Type | CZ FZ;N or P |
| Crystal Direction | {100}{111} |
| Resistivity (Ohm/cm) | 0.003-50 |
| Thermal conductivity(J/K.M.S) | 163.3@273K |
| Density | 2.33g/cm³ at20℃ |
| Melting point | 1410℃ |
| Boiling point | 3265℃ |
| Knoop Hardness | 1150 |
| Transparency Range | 1000nm-10000nm，30000nm-300000nm |
