Single crystal sapphire prisms are ideal for demanding applications (such as laser systems) and harsh environments because of their extreme surface hardness, high thermal conductivity, high dielectric constant and resistance to common chemical acids and alkalis. Sapphire is the second hardest crystal next to diamond and, because of their structural strength, sapphire crystal lenses can be made much thinner than other common materials. Chemically, sapphire is single crystal aluminum oxide (Al2O3) and is useful in a transmission range from 0.15 to 5.5μm. Customized lenses are offered upon customer’s request.
| Physical and optical properties | |
| Transmission Range | 0.17 to 5.5 μm |
| Refractive Index | No 1.75449; Ne 1.74663 at 1.06 μm (1) |
| Reflection Loss | 14% at 1.06 μm |
| Absorption Coefficient | 0.3 x 10-3 cm-1 at 2.4 μm (2) |
| Reststrahlen Peak | 13.5 μm |
| dn/dT | 13.1 x 10-6 at 0.546 μm (3) |
| dn/dμ = 0 | 1.5 μm |
| Density | 3.97 g/cc |
| Melting Point | 2040°C |
| Thermal Conductivity | 27.21 W m-1 K-1 at 300K |
| Thermal Expansion | 5.6 (para) & 5.0 (perp) x 10-6/K * |
| Hardness | Knoop 2000 with 2000g indenter |
| Specific Heat Capacity | 763 J Kg-1 K-1 at 293K (4) |
| Dielectric Constant | 11.5 (para) 9.4 (perp) at 1MHz |
| Youngs Modulus (E) | 335 GPa |
| Shear Modulus (G) | 148.1 GPa |
| Bulk Modulus (K) | 240 GPa |
| Elastic Coefficients | C11=496 C12=164 C13=115 C33=498 C44=148 |
| Apparent Elastic Limit | 300 MPa (45,000 psi) |
| Poisson Ratio | 0.25 |
| Solubility | 98 x 10-6 g/100g water |
| Molecular Weight | 101.96 |
| Class/Structure | Trigonal (hex), R3c |
