Nov 6 2020
A new study by researchers at Tel Aviv University will enable cameras to identify colors that cannot be recognized even by ordinary cameras and the human eye.
The technology can be applied to image gases and substances like sodium, carbon, and hydrogen, each of which has a distinct color in the infrared spectrum. It can also be used to image biological compounds existing in nature but “invisible” to the ordinary cameras or naked eye.
It has innovative applications in a range of fields such as computer gaming, photography, and the disciplines of security, astronomy, and medicine.
The study was performed by Dr. Michael Mrejen, Yoni Erlich, Dr. Assaf Levanon, and Professor Haim Suchowski of TAU’s Department of Physics of Condensed Material. The study findings were published in the October 2020 issue of Laser & Photonics Reviews.
The human eye picks up photons at wavelengths between 400 nanometers and 700 nanometers—between the wavelengths of blue and red. But that's only a tiny part of the electromagnetic spectrum, which also includes radio waves, microwaves, X-rays and more.
Dr Michael Mrejen, Department of Physics of Condensed Material, American Friends of Tel Aviv University
Mrejen added, “Below 400 nanometers there is ultraviolet or UV radiation, and above 700 nanometers there is infrared radiation, which itself is divided into near-, mid- and far-infrared. In each of these parts of the electromagnetic spectrum, there is a great deal of information on materials encoded as 'colors' that has until now been hidden from view.”
The team describes that colors in such parts of the spectrum are of great significance since several materials have a distinct signature that is expressed as a color, particularly in the mid-infrared range. For instance, cancer cells could be detected easily as they possess a higher concentration of molecules of a specific type.
Current infrared detection technologies are costly and mostly incapable of rendering those “colors.” In the area of medical imaging, experiments have been carried out where infrared images are transformed into visible light to determine the cancer cells by the molecules.
So far, this transformation needed highly advanced and costly cameras, which were not essentially accessible for normal use.
However, as part of their study, scientists of TAU could develop low-cost and efficient technology that could be fitted on a typical camera and enables, for the first time, the transformation of photons of light from the whole mid-infrared region to the visible region, at frequencies that can be picked up by the human eye and the regular camera.
We humans can see between red and blue. If we could see in the infrared realm, we would see that elements like hydrogen, carbon and sodium have a unique color. So an environmental monitoring satellite could ‘see’ a pollutant being emitted from a plant, or a spy satellite would see where explosives or uranium are being hidden. In addition, since every object emits heat in the infrared, all this information could be seen even at night.
Haim Suchowski, Professor, Department of Physics of Condensed Material, American Friends of Tel Aviv University
The researchers have registered a patent for their invention and are now advancing the technology via a grant from the Innovation Authority’s KAMIN project. They have already met several Israel-based and international companies.
Mrejen, M., et al. (2020) Multicolor Time-Resolved Upconversion Imaging by Adiabatic Sum Frequency Conversion. Laser & Photonics Reviews. doi.org/10.1002/lpor.202000040.