For a better view

Antireflective structures following the example of moth eyes

Photo: Car Dashboard -right side- scratch-resistant anti-reflection coating AR-hard® (Fraunhofer IOF )

Being able to see better in the dark than humans is essential for the survival of many animal species. That is why for instance nocturnal moths have fine structures on the surface of their eyes that prevent the reflection of light very effectively. This gives the animals a twofold advantage: It improves their vision because they can also use the dim remaining light almost completely. At the same time, the missing reflection of their eyes makes them practically invisible to their predators.

Surface engineering uses an effect similar to this structure of moths’ eyes in order to apply antireflection coatings to glass or transparent plastics. An antireflective coating of surfaces that is as effective as possible is especially important in the area of optics. Without antireflection coatings, several percent of the light would get lost at every interface of an optical system. Therefore, optical systems consisting of multiple lenses in particular are inconceivable without antireflective coatings today.

Researchers from Jena have developed a specific plasma-etching technique that can be used for the antireflective coating of polymer surfaces. The advantage of the technique is that it can be applied to both plane parts and strongly curved optical lenses or irregular structures.

With this, it is possible to apply antireflective coatings to transparent polymers like PMMA, polycarbonate and different newer types of thermoplastic polymers. Based on these polymers, optical lenses are made that can be used in the areas of camera technology, microscopy, sensor and medical technology.

Another application is the constantly growing display market. Especially in automotive engineering, transparent plastics in optical quality are to be used increasingly as interior covers in vehicles. This requires a good readability of the instrument panels even during disturbing incidence light which can only be achieved by antireflective coatings.

More information about Fraunhofer Institute for Applied Optics and Precision Engineering IOF