Current night vision devices are large, heavy, and generally expensive, which are the reasons this technology is often limited to a privileged group of users, such as the military. Unsurprisingly, not everyone is willing spend hundreds of dollars to see in the dark with a two-pound device on their heads. But what if everyday eyewear could provide night vision? A group of scientists in Australia thinks it might be possible.
Scientists at the ARC Center of Excellence for Transformative Meta-Optical Systems (TMOS) have recently published a paper in Advanced Materials that addresses this issue with what they call “nonlinear infrared upconversion technology.” In other words, they’re developing a night vision solution that aims to work in a thin film or lenses with a minimal width. Experts pointed out that the miniaturization of system components could drive widespread adoption of these solutions.
Night Vision in Everyday Glasses
To better understand the center's research, it's important to know the basics of how analog night vision works. This is a complex system where an objective lens collects photons from the environment and passes them through an electronic intensifier tube. The photons flow into a photocathode, which converts them into electrons. These electrons pass through a phosphor plate and become photons again, reproducing the scene in shades of green and black.
Considering that analog night vision includes at least two types of lenses—in addition to a photocathode, a photomultiplier, and other electronics—it may be difficult to imagine an alternative as seemingly basic as a film. But the scientists have something simpler in mind: Instead of using so many elements, they're proposing a metasurface that boosts the energy of photons and pulls them into the visible light spectrum without requiring electron conversion.
Representation of an actual night vision system.
As we mentioned earlier, their proposed alternative features a key material. While researchers have used gallium arsenide surfaces in the past, they’re now turning to lithium niobate. For decades, experts have used this crystal in optics and photonics applications, such as optical modulators for telecommunications. This material is entirely transparent in the visible range, allowing the photon beam to spread widely over its surface.
Study co-author Laura Valencia Molina points out that many people thought the upconversion of high-efficiency infrared to a visible state was impossible due to information loss. However, the team’s latest findings show they’ve overcome these limitations. Time will tell whether this technology will transform how manufacturers produce their night vision goggles.
Images | TMOS | R.Louis Mac Photo | Lode Lagrainge
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