Like some snakes use infrared to “see” at night, similar “viper” vision could improve the sensitivity of night-vision cameras. Researchers have developed detectors that enable more information to be extracted from the object in the dark. When looking at a person at night through night-vision goggles, the person’s infrared signature is visible. The person may have a hidden weapon that emits a different wavelength of infrared light but it cannot be seen even with a presently available, cryogenically cooled camera.
The new infrared detector doesn’t need liquid nitrogen cooling it down to an extreme -321° to be sensitive enough to detect different wavelengths of infrared light. It also operates much faster than existing night-vision cameras that don’t require cooling but are slow to process images.
Humans see light in the electromagnetic spectrum that has wavelengths from about 400 to 700 nanometers long, which is known as the visible light spectrum. With much longer wavelengths that extend to about 16,000 nanometers, the new detector can discern the different wavelengths in the invisible infrared domain. It does this by picking out different objects emitting different wavelengths. Current night-vision cameras can’t isolate the different objects based on their distinct infrared wavelengths and instead integrate or lump the wavelengths all together, so that what may be several separate objects are only seen as one through the infrared lens.
With the new technology, additional infrared “colors” could be assigned to represent items that reflect different wavelengths of infrared light, in addition to the standard colors of green, orange, or black seen in night vision. For astronomers, this means the potential to have new telescopes that see information that was previously invisible in the infrared domain. For chemical and biological disaster areas, or even monitoring pollution, it means taking a picture to receive a spectral analysis of the gases present in an area, such as carbon monoxide or carbon dioxide, based on how infrared light reacts with chemical molecules.
The challenge in developing the highly sensitive but uncooled infrared detector was engineering the two-dimensional nanomaterial graphene into a material that can carry an electric current. This was achieved by designing the material to be asymmetric, so the temperature difference created from absorbed light hitting the different parts of material caused electrons to flow from one side to another, thus creating a voltage.