Because Aluminum surfaces react with the atmosphere and lose reflectivity, most, but not all, Aluminum mirrors are used with a thin film optical coating, to improve reflectance, and durability.
Laser Beam Products offer several coatings:
- Electroplated Gold, for near and far infra red use
- MaxR for 10.6um, high reflectivity for CO2 lasers
- Protected Silver for visible and near infra red use.
It is possible to have a thin film vacuum deposited coating optimized for other specific wavelengths, or several multiple wavelengths.
To improve the laser damage resistance, and reduce scatter, LBP Aluminum mirrors have an intermediate layer of electroless nickel deposited. This gives an amorphous, non crystalline surface of exceptional smoothness. Electroless Nickel also protects the whole of the mirror from oxidation.
Aluminum mirrors are chemically polished, the surfaces are super smooth and are free of turning lines, fly cutting arcs, and diffractive patterns that lower the surface quality of diamond turned mirrors.
Finally our proprietary stress relieving, and heat treatment gives long term stability and performance across a wide range of temperatures.
Aluminum based mirrors are a good alternative to Silicon mirrors in laser scanning and galvo applications, as Aluminum is far easier to engineer into complex shapes. Further weight saving is possible by using ribbed and pocketed designs on the rear of the mirrors.
Laser Beam Products can make mirrors from intricately engineered parts where one face is needed to be a laser grade mirror surface. We can make flat and spherically curved Aluminium optics with various coatings.
Care should be taken in using metal optics to avoid Galvanic corrosion, In the presence of moisture or water cooling dissimilar metals will cause electrochemical decomposition. Electroless Nickel plating can reduce this problem.