Nanocrystals could aid night vision Sipa Press/Rex/Shuttertock

Fancy some glasses that switch to night vision when the sun goes down? Nanocrystals that turn infrared radiation into visible light could be just what you need.

Night-vision binoculars are currently used by soldiers to track enemies in the dark, but are large and cumbersome. These devices detect infrared waves emitted by warm bodies, convert them into electricity and produce visual displays in front of your eyes.

Now, Dragomir Neshev at the Australian National University in Canberra and his colleagues have developed nanocrystals that see directly into the infrared part of the spectrum and could be incorporated into regular glasses.


The nanocrystals, which are made of aluminium, gallium and arsenide, are each 500 times narrower than a human hair and can be applied to glass as ultra-thin, lightweight films.

Each nanocrystal acts like an antenna that receives and concentrates infrared heat radiation so that it turns into visible light. This process is known as second harmonic generation.

So far, Neshev’s team has shown that the nanocrystals can shift high-intensity laser-generated infrared waves into the visible spectrum. The results were presented at the Australian Institute of Physics Congress in Brisbane, Australia, last week.

Into the dark

Converting infrared radiation from warm bodies is trickier because it has lower intensity than laser light. The prototype night-vision glasses will need to incorporate a tiny laser similar to those found in pointers that use them. This will release laser light that combines with incoming infrared waves, thus moving objects viewed in the dark into the visible spectrum.

In addition, different sized nanocrystals will be mixed together in the thin film so that different frequencies of infrared radiation can be converted.

The question now is, how will the infrared world of darkness look when transformed into colour?

“I’ve been scratching my head over this, but to tell you the truth, I don’t know,” says Neshev. It’s likely that warmer objects will look bluish and cooler ones reddish, he says.

Aside from having obvious benefits for the military, the team has been creative in coming up with other possible applications. “There’s the possibility of playing night golf,” Neshev suggests. The aim is to build a successful prototype within five years.

Journal reference: Nano Letters, DOI: 10.1021/acs.nanolett.6b03525