Specifications:
| Materials | Sapphire crystals | Diameter Range | ~ 250mm |
| 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 | No coating or single layer MgF2 |
Basic 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 |
| 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 |
Sapphire or aluminum oxide (Al2O3) is single crystal and is useful in a transmission range from 0.2 - 5.5μm, sapphire is suitable for MWIR 3-5μm thermal imaging applications. Sapphire Windows are made from single crystal sapphire, they are ideal for demanding applications for 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 diamonds and, because of their structural strength, sapphire windows can be made much thinner than other common dielectric windows with improved transmittance.
Curves:
Transmission curve of the Sapphire windows (no coating)
 Crystals Windows02.jpg)
 Crystals Windows01-500x400.jpg)
 Crystals Windows01-50x40.jpg)