Want glasses that help you see in the dark? You might have seen characters in an action movie use night vision goggles. Those show a ghostly green image that makes objects visible in the dark. Now researchers are developing a new technology. They want to use ultra-thin layers of nanocrystals (teeny-tiny crystals) to make infrared light visible.     

Devices like night vision goggles can detect energy in the light spectrum that is invisible to the human eye. Infrared (sometimes called IR) is a type of radiation that has wavelengths longer than those of visible light. It is outside the range that humans can see. But God has no such limitations. Psalm 139:12 says of God, “even the darkness is not dark to you; the night is bright as the day, for darkness is as light with you.”

Infrared devices like goggles and cameras convert IR to an electrical signal. That signal shows on a screen. But this technology is bulky, heavy, and disrupts normal vision.

There are also all-optical alternatives. These don’t use electrical signals. Instead, they directly convert IR into visible light. The visible light can then be captured by the eye or a camera.

These technologies combine IR with a laser beam inside a material called “nonlinear crystal.” The crystal then emits light in the visible spectrum. However, nonlinear crystals are also bulky. Plus, they’re expensive and they can detect only a limited range of light. So scientists want to make the all-optical approach work better.

The goal is to produce a lightweight film that can be applied as a thin layer on glasses or other lenses. Powered by a tiny built-in laser, the film will allow people to see in the dark.

Carefully designed layers of nanocrystal are called “metasurfaces.” Metasurfaces are ultra-thin and ultra-light. They can manipulate the color or frequency of the light that passes through them. This makes metasurfaces a good platform to convert infrared photons (particles) to visible light.

The scientists designed a metasurface made of hundreds of incredibly tiny crystal antennas. They put the metasurface on a transparent glass, forming a layer of nanocrystals thinner than a human hair.

To test the metasurface, they shined infrared images on the glass. It worked! Those infrared images were converted to visible green images.

The military, police, security guards, hunters, and campers all sometimes need night vision devices. The technology could be helpful in other industries too. It could help monitor and maintain food quality control. It could also be used for mapping and measuring.