New Laser Identifies Materials from a Mile Away

Joseph Meola of Air Force Research Labs conducting measurements on laser light bounced back from various samples placed a mile away on the ground from a prototype laser at Wright Patterson Air Force Base. Image credit: Anthony Absi, Air Force Research Labs
Engineers from the University of Michigan are developing a new laser that can show what objects are made of from a long distance. This could help military aircraft locate different types of enemy targets as well as have several other more benign uses.
Unlike most existing lasers, the one developed by the University of Michigan team give off a tight beam packed with columns of light covering a range of wavelengths and is known as super-continuum laser (most lasers emit light in just one wavelength, or color). The new laser which uses off-the-shelf telecommunications technology, operates at the infrared part of the light spectrum and is therefore invisible to the naked eye.
The researchers at the University of Michigan decided to use an infrared laser since it contains what they call “spectral fingerprinting range” or frequencies at which the researchers can detect echoes of the vibrations of the molecules that make up a solid substance. Since different substances absorb and reflect different wavelengths, shining the new laser on a target can allow researchers to analyze the light coming back from the object and tell what is the chemical composition of that object.
According to Mohammed Islam, a professor of electrical engineering and computer science and biomedical engineering at the University of Michigan: “The military uses spectral fingerprinting to identify targets today to a certain extent, but it relies on the sun for the light, which can be a problem on a cloudy day or at night”. And while broadband infrared lasers already exist, the one developed by the University of Michigan team is more powerful. Islam’s team already tested a 5-watt prototype at a distance of over a mile, built a stonger 25.7 watt version and it is now working on an even more powerful 50-watt prototype, which is set to be tested later this year.
The higher power of the new super-continuum laser can give aircrafts for the first time the capability to perform analysis of potential target while flying at a safe altitude. This is compared to most existing detectors which can operate at a very close range. The technology can also help improve the full-body airport screening technologies currently in existence.
More information on the new laser can be found on the University of Michigan website.


A video showing the new super-continuum laser

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