In addition to the T* coating a further protective coating is deposited on the outer surface of all lens elements used on ZEISS Victory models. It ensures that water beads off without residue immediately and that dirt and fingerprints do not adhere to the surface.
This allows fast, easy cleaning of these extremely smooth surfaces without any risk of damaging the valuable optics. The namesake and inspiration for the LotuTec® coating of ZEISS are the leaves of the lotus flower and their hydrophobic effect.
Operating principle
Without the LotuTec® coating, later drops, for example, would stick to the surface and, due to the attraction between water and glass, adhere easily. The angle at which the edge of the water drop touches the glass surface is called contact angle. Flat, adhesive drops have low contact angles.
Water-repellant coatings, on the other hand, create few contact points. The drops become ball shaped similar to those on a hot plate and run off. The contact angle as a measure of the hydrophobic effect of the coating is very high then. Measurements on the LotuTec® show return values clearly above 110° which documents the very high effectiveness and far exceeds manyother hydrophobic coatings.
With the LotuTec® coating a large contact angle results in globular water drops that roll off.
Without the LotuTec® coating the contact angle of max. 95° results in water drops that adhere relatively strong.
Durability
The same high standards and test methods used to guarantee the durability of T* coatings for decades are applied to determine the durability and resistance of the LotuTec® coating to abrasion.
The LotuTec® coating was developed at ZEISS for eyeglass lenses originally where it has proven its value for many years. Special modifications enabled the transfer of this sophisticated coating technology to the high-quality glass used for ZEISS Sports Optics products.
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