Knight Optical’s Sapphire Windows are engineered for oceanographic and offshore systems demanding optical clarity and maximum resilience. Fabricated from crystalline Al₂O₃, these windows withstand punishing subsea conditions—resisting intense pressure, thermal variation, saltwater corrosion, and high-energy radiation.
With optical transmission from 150nm to 5.5µm and a hardness second only to diamond, they are ideally suited for high-precision sensing, imaging, and laser-based instrumentation in challenging marine environments.
Available in both c-cut and random-cut configurations, the windows meet distinct application needs: c-cut for low-birefringence and minimized image distortion, and random-cut for robust mechanical integrity in non-critical optics.
Knight Optical also offers extensive customization, from precision edge finishing and optical coatings (including BBAR and DLC) to integration into sealed sub-assemblies. Each unit is individually inspected using in-house metrology to guarantee superior optical fidelity and mechanical tolerances, meeting the exacting requirements of scientific and industrial subsea deployments.
| Diameter Range | <5mm to 300mm |
| Diameter Tolerance | ±0.1mm |
| Centre Thickness | Up to 50mm |
| Thickness Tolerance | ±0.05mm |
| Clear Aperture | 90% |
| Centration Tolerance | <1 arc minute |
| Form Error | <λ/4 @ 633nm over aperture |
| Surface Radius Tolerance | <1 fringe over aperture |
| Linear Dimension | Up to 120mm |
| Linear Tolerance | ±0.1mm |
| Angular Tolerance | <5 arc minutes |
| Surface Quality | 40-20 scratch/dig |
| Coatings Available | BBAR @ 1–5µm, DLC @ 1–5µm |
| Edge Finish | Ground, blacked |
| Chamfer | 0.3 x 0.3mm @ 45° |
| Material | Sapphire (Al₂O₃), HK1370kg/mm² |
| Transmission Range | 0.15µm to 5.5µm |
| Refractive Index | 1.75 |



