Antireflective surfaces reach high efficiency by mimicking nature

24 noviembre 2016

Moth's eyes have evolved to prevent light from reflecting off them. This particular feature is becoming important for producing better antireflective nanostructured surfaces.>/p>

Moths are a group of insects related to butterflies, belonging to the order Lepidoptera. There are thought to be approximately 160,000 species of moths, not all of them have been described. Most moth species are nocturnal and they are known in every house because they frequently fly in circles around artificial lights. Moth's eyes have evolved to prevent light from reflecting off them. This particular feature is becoming important for producing better antireflective nanostructured surfaces. Antireflective surfaces –common in cell phones, TV screens and solar panels– are usually made of multilayered films. They only work at a specific spectral range, which reduces their efficiency. To overcome this, German researchers have looked to the structure of moths' eyes, which transmit a broad spectrum of light sources. This helps moths navigate in the dark, eliminating at the same time reflections that would otherwise alert predators.

Almost zero reflection

Teams at the Max Planck Institute for Medical Research, in Heidelberg, and the University of Applied Sciences in Jena have worked together to make lenses up to 25mm in diameter with nanopillared surfaces that have 99.8% transmittance and just 0.02% reflectance for a wide wavelength range covering visible and near infra-red. This can be described as a near-perfect transmission of light with almost zero reflection.

Compared to other multilayer thin film coatings, these new antireflective surfaces not only operate at a much broader wavelength range, they are also mechanical stable to resist human touch or contamination, show a 44% laser-induced damage threshold and are suitable for bended interfaces such as microlenses.

For the moment, the cost associated with this technique could limit wide-scale adoption and it will be more applicable to high-end optical devices. It could find uses in touchscreens and sensors and improve the performance of high power lasers used in micromachining and medical procedures.

 

CREDIT: Wikipedia/John Alan Elson

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