For stealthy fight at night, moths have evolved eyes that are non-reflective, according to the Tokyo University of Science, which has used the animals periodic nanometric surface structure as inspiration for a coating for displays.

Tokyo-University-of-Science-moth eye anti-reflection
Rather than looking polished, the eye coating causes most incident light to bend at the surface an transmit through the eye instead of being reflected from it.
Tokyo-University-of-Science-moth eye anti-reflectionWorking with company Geomatec, scientists from the university have been trying to make nanostructures that mimic moth eyes and can be made as scale without being too expensive.
Making moulds from glassy carbon etched with an oxygen ion beam worked, but was not scalable.

“Producing glassy carbon substrates requires the use of powder metallurgy technology, which is difficult to use to produce moulds with a large area,” said Professor Jun Taniguchi. “To overcome this limitation, we tried using only a thin layer of glassy carbon deposited on top a large regular glass substrate.”
Tokyo-University-of-Science-moth eye anti-reflectionTo get this scheme to work, the team switched to inductively coupled plasma (ICP) etch from the previous electron-cyclotron resonance ion source – both can etch glassy carbon with oxygen ions, but ICP produces an ion beam better suited to large areas.
In slightly more detail, the glass substrate was sputtered with titanium as an adhesion layer, then sputtered with glassy carbon, and then oxygen etched. The necessary surface structures form spontaneously without additional patterning.
Once made, the mould was used to produce a transparent film with a moth-eye-like nanostructure from UV-curable resin by dripping on liquid resin and removing it after curing.
Tokyo-University-of-Science-moth eye anti-reflection“The optical properties of this film were remarkable,” according to the university. “Its reflectance toward light in the visible range was only 0.4%, ten times lower than that of a similar film without the moth-eye nanostructure. What’s more, the transmittance of light through the material was also increased, meaning that no trade-off in optical properties occurred as a result of using the film to reduce reflected light.”
Tokyo-University-of-Science-moth eye anti-reflectionIf they can be made on a metre scale, “We could use these films to improve visibility in flat panel displays, digital signs, and transparent acrylic plates”, said Geomatec CTO Hiroyuki Sugawara. “Moreover, anti-reflective coating could also be an efficient way to improve the performance of solar panels.”
The research is published as ‘Moth-eye structured mold using sputtered glassy carbon layer for large-scale applications‘ in the journal Micro and Nano Engineering. The whole paper is available without charge.