Sapphire Windows

Knight Optical can supply a range of custom Sapphire (Al₂O₃) window options.  Sapphire is one of the hardest minerals on Earth and its optical material properties are available for use in the range from UV up to about 5µm.  We provide custom sapphire windows at zero degree plane, or c-cut plane and also random cut plane which is usually cut along a plane that is 60° off-axis as the growth in this direction is the easiest to grow.

Random cut is anyone that is not the c-cut angle.  Sapphire can fluoresce and that depends upon the concentration of other minerals within the lattice, for example Iron (Fe) or Chromium (Cr).  Clear Sapphire might fluoresce orange when illuminated by UV light if impurities are in the crystal.  Fluorescent free Sapphire has to be grown from ‘pure’ feedstock and seed and in an environment that cannot place impurities into the lattice.

Our custom Sapphire windows can be polished to a high standard, but as it is the second hardest mineral on Earth it must be subject to high forces to get the polish.  Therefore, windows made from Sapphire must have a thickness to diameter ratio of at least 10:1, that is, greater than 10mm thick for a 100mm diameter disk.  Sapphire is inert and resistant to attack from most processing environments, such as hydrofluoric acid.  Sapphire has a melting point over 2000°C with a high thermal conductivity makes it suitable for use in harsh environments.

Sapphire is ideal for use as a window where high radiation resistance is required from the UV to about 5µm. We can supply all grades of sapphire from 5 to 300mm dia and up to 50mm thick.  We can achieve a ¼ wave polish and scratch dig better than 40-20. All custom sapphire windows can be supplied uncoated or antireflective coated for increased performance.

Other custom sapphire components we offer are diamond turned aspheric and spherical lenses, sapphire prisms and ground blanks.

Every component is individually tested by our highly skilled technicians in our state of the art metrology lab to ensure all components meet our high quality standards. Contact our multilingual technical sales team and discover how Knight Optical’s high quality sapphire windows and service can improve your instrumentation and supply chain experience.

View “available stock” tab for a range of quality stock sapphire windows in a range of diameters and thicknesses to meet most applications.  If you require sapphire windows to a smaller size or a custom aperture we are able to machine our stock windows at short notice, please enquire.