A new laser shows what objects are made of and could help military aircraft identify hidden dangers such as weapons arsenals far below.

The system, which is made of off-the-shelf telecommunications technology, emits a broadband beam of infrared light. While most lasers emit light of one wavelength, or color, the new super-continuum lasers give off a tight beam packed with columns of light covering a range of wavelengths — a blend of colors. Because the beam is in the infrared region, it is invisible to human eyes.

The infrared contains what scientists refer to as the "spectral fingerprinting range" — frequencies at which they can detect echoes of the vibrations of the molecules that make up a solid substance. A substance's spectral fingerprint reveals which wavelengths of light it absorbed, and which it reflected. Different substances absorb and reflect different wavelengths. By shining the new laser on a target and analyzing the reflected light, the researchers can tell the chemical composition of the target.

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Also: Learn about a Simple Laser Communications Terminal for Downlink From Earth Orbit.


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