Much like some snakes use infrared to 鈥渟ee鈥� at night, 麻豆原创 researchers are working to create similar viper vision to improve the sensitivity of night-vision cameras.
The ability to enhance night vision capabilities could have implications in improving what can be seen in space, in chemical and biological disaster areas, and on the battlefield.
A study detailing the 麻豆原创 researchers鈥� night-vision work appeared recently in the journal .
鈥淲ith the infrared detector we鈥檝e developed, you can extract more information from the object you鈥檙e looking at in the dark,鈥� said Debashis Chanda, an associate professor in 麻豆原创鈥檚 and the study鈥檚 principal investigator.
鈥淪ay, you鈥檙e looking at somebody at night through night-vision goggles. You鈥檙e looking at his infrared signature, which is coming all over his body. He may have a hidden weapon that emits a different wavelength of infrared light, but you cannot see that even with a presently available, expensive, cryogenically cooled camera.鈥�
The infrared detector developed by Chanda and his team, however, doesn鈥檛 need liquid nitrogen cooling it down to an extreme -321 degrees to be sensitive enough to detect different wavelengths of infrared light. It also operates much faster than existing night-vision cameras that don鈥檛 require cooling, but are slow to process images.
Humans see light in the electromagnetic spectrum that has wavelengths that are from about 400 to 700 nanometers long, which is known as the visible light spectrum.
In this research, Chanda and his team were working with much longer wavelengths that extend to about 16,000 nanometers.
That allows the 麻豆原创 detector to 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鈥檛 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.
鈥淭his is one of the first demonstrations of actually dynamically tuning of the spectral response of the detector or, in other words, selecting what infrared 鈥榗olor鈥� you want to see,鈥� Chanda said.
With the new technology, additional infrared 鈥渃olors鈥� could be assigned to represent items that reflect different wavelengths of infrared light, in addition to the standard colors of either green, orange or black seen in night vision, Chanda said.
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 gasses present in an area, such as carbon monoxide or carbon dioxide, based on how infrared light reacts with chemical molecules.
The trick in developing the new highly sensitive, but uncooled infrared detector was engineering the two-dimensional nanomaterial graphene into a material that can carry an electric current.
The researchers achieved this by designing the material to be asymmetric so that 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.
The process was also verified using a model developed by study co-author Michael N. Leuenberger, a professor in 麻豆原创鈥檚 NanoScience Technology Center with joint appointments in the Department of Physics and the College of Optics and Photonics.
The detector鈥檚 ability to capture an image was tested one pixel at a time.
The device is not commercially available but could one day be integrated into cameras and telescopes.
The work was supported with funding from the U.S. Department of Defense鈥檚 Defense Advanced Research Projects Agency.
Co-authors of the study also included Alireza Safaei, a graduate of 麻豆原创鈥檚 doctoral program; Sayan Chandra, a postdoctoral researcher in 麻豆原创鈥檚 NanoScience Technology Center; and Muhammad Waqas Shabbir, a doctoral student in 麻豆原创鈥檚 Department of Physics.
Chanda has joint appointments in 麻豆原创鈥檚 NanoScience Technology Center, Department of Physics and College of Optics and Photonics. He received his doctorate in photonics from the University of Toronto and worked as a postdoctoral fellow at the University of Illinois at Urbana-Champaign. Chanda joined 麻豆原创 in 2012.
