Researchers have developed a revolutionary thin infrared filter for night vision that can be integrated into everyday glasses, allowing simultaneous imaging of the infrared and visible light spectrum. This innovation will revolutionize night vision technology, making it lighter and more practical for daily use and potentially improving safety in low-light conditions.

Scientists at TMOS, ARC’s Center of Excellence for Transformative Meta-Optical Systems, have made significant progress in their journey to bring a new approach to night vision technology, creating an infrared filter that is thinner than a piece of plastic wrap and could one day be used. It can be placed over everyday glasses, allowing the wearer to view infrared and visible light spectrums simultaneously.

Night vision devices were primarily used by the military, hunters who wanted to carry multi-purpose binoculars, or photographers who liked to carry heavy lenses. This is due to the weight and volume of the equipment. An ordinary person does not go for a night run with an extra kilo on his forehead.

Improving daily night vision

Miniaturization of night vision could lead to widespread adoption. Creating night vision filters that weigh less than a gram and can fit like a film over traditional glasses paves the way for new everyday applications. Consumer night vision goggles that allow the wearer to see the visible and infrared spectrums simultaneously can contribute to safer driving in the dark, safer night walks, and less work in low-light conditions that currently require large and often obtrusive headlights.

In a study published in the journal Advanced Materials, TMOS researchers at the Australian National University demonstrate an improved technology for nonlinear enhancement of infrared vision using a non-native lithium niobate metasurface.

Optimization of the night vision process

Traditional night vision technology requires infrared photons to pass through a lens and then encounter a photocathode, which converts those photons into electrons and then pass through a microchannel plate to increase the number of electrons produced. These electrons passing through the phosphor screen are converted back into photons, creating an enhanced visible image that can be seen with the naked eye (Figure 1.1). These elements require cryogenic cooling to prevent increased thermal noise. As explained above, a high-quality night vision system is heavy and bulky. Additionally, these systems often block visible light.

Metasurface-based upconversion technology requires fewer elements, significantly reducing the footprint. Photons pass through a resonating metasurface and mix with the pump beam (Figure 1.2). A resonant metasurface increases the energy of photons, attracting them into the visible light spectrum; There is no need to convert electrons. It also operates at room temperature, eliminating the need for bulky and heavy cooling systems.

Figure 1.2 Schematic of the metasurface-based infrared conversion setup. Contributors: Laura Valencia Molina, Australian National University

Improving image processing technology

Additionally, traditional infrared and visible imaging systems cannot produce identical images because they capture images from each spectrum side by side. Using up-conversion technology, imaging systems can capture both visible and invisible images in a single image.
The work is an improvement on the researchers’ original technology involving the gallium arsenide metasurface. Their new metasurface is made of lithium niobate, which is completely transparent in the visible range, making it much more efficient. Additionally, the photon beam spreads over a larger surface area, limiting angular data loss.

Expectations for increasing conversion efficiency

Lead author Laura Valencia Molina says: “People say that highly efficient infrared-to-visibility conversion is not possible due to the amount of information that cannot be collected due to angular losses in non-local metasurfaces. We overcome these limitations and experimentally demonstrate highly efficient image conversion.”

Author Rocio Camacho Morales says: “This is the first demonstration of high-resolution upconversion imaging from 1550 nm infrared to 550 nm visible light on a non-native metasurface. We choose these wavelengths because 1550 nm infrared light is widely used for telecommunications and 550 nm is human light.” “Future research will include expanding the wavelength range to which the device is sensitive to achieve broadband IR imaging, as well as investigating image processing, including edge detection.”

Future implications and applications

Lead researcher Dragomir Neshev says: “These results promise significant opportunities for the surveillance, autonomous navigation and bioimaging industries, among others. Reducing the weight and power requirements of night vision technology means that the work done by meta-optics and TMOS will enable Industry 4.0 and technology to “It’s an example of how critical it is for future extreme miniaturization.”