The technology of anti-reflective coating
The procedure to the reduction of reflection on lenses was already developed in 1936 the by Carl Zeiss. Only two decades later (1959) the first lenses with a reducing reflective layer on mineral lenses where in serial production.
Simple antireflection coatings with blue residual reflection were quickly superseded by multilayer antireflection coatings and offered a minimized residual reflection, but the requirements continued to rise. The disadvantage of a rough surface with antireflection coatings and thus poor cleaning properties was countered with a clean coating. Then the trend came to plastic lenses and a really seemingly secure technology could be reinvented. In Particular with plastic lenses the additional need for hard coatings developed, to increase the scratch resistance.
Modern hard coatings achieve by now a comparable resilience like mineral lenses. In a nearly pure plastics market the coating technology has reached a level that up to 12 layers are only responsible for the anti-reflective coating. Superhydrophobicity and antistatic layers have done out of their way to actually eliminate many objections against coated plastic lenses.
Nowadays the coatings consist of:
- Super-hard coating Hard layer with increased silicon content thanks to nanotechnologies
- An adhesion agent between lacquer and AR coating
- Antireflection coating
- Antistatic layer
- Superhydrophobic Clear Coat coating (lotus effect)
- Adhesive layer for improved processing
But what is still to come?
Blue Light Reduced Coating
Firstly, these follow the concept of Blue Blocker, in which the more refracting proportion of blue light is filtered to avoid stray light and increase contrast. Secondly, it is of modern light sources (LEDs) and displays (flat screens) from a high proportion of blue light, which is responsible for eye fatigue. Since a high UV / blue light component has a negative influence on the development of age-related macular degeneration is attributed, this coating further has a preventive effect.
We provide this coating with our glass-brand One Vision as NanoTec Blue.
Pure UV coatings are dedicated to the contrary only the UV light and let the blue light through. This missing functionality is taken in account for aesthetic reasons since a pure UV coating is, opposed to blue light coating, completely colorless. There is not more to say about the advantage of the coatings. Everyone wants 100% UV protection in his sunglasses to prevent accelerated aging of the eyes or UV-related eye damage.
Achromatic (color-neutral coatings)
A occasionally occurring trend, which could not yet prevail in the masses, are color-neutral antireflection coatings. The idea is that there is no color change in reflectance (green residual reflection) with almost equivalent reduction in reflection.