Hydrophobic coatings
Fingerprints and other handling marks detract from the appearance of high quality optical coatings. The problem is acute on high performance anti-reflection coatings used on consumer products such as spectacle lenses or display windows used on mobile phones, PDA's. ATMs etc..
The problem is neatly overcome by adding a hydrophobic "topcoat" to the AR coating stack. This coating makes the product feel silky smooth and water, grease and skin oils are easily removed. The effectiveness of the hydrophobic coating is measured using a water contact angle. A standard hydrophobic treatment will produce a water contact angle >900, while a super-hydrophobic topcoat will produce a water contact angle exceeding 1100
A display window showing the benefits of easy clean AR coatings
A water contact angle of 1100 measured on a hydrophobic topcoat.
The hydrophobic process is a standard option on optical coating systems from Applied Multilayers. The hydrophobic material is contained in a "pill" which is released onto the substrates by thermal evaporation.