US: A new laser that can show what objects are made of 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, super-continuum lasers like this one give off a tight beam packed with columns of light covering a range of wavelengths – a blend of colors. Because this beam is in the infrared region, it”s invisible to human eyes. But it can illuminate deep information.
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. So by shining the new laser on a target and analysing the reflected light, the researchers can tell the chemical composition of the target.
These higher power lasers could give an aircraft flying at higher altitudes the capacity to illuminate a region with a brightness comparable to sunlight, and then image that region. Many chemical sensors in use today work at close range, but few, if any, can do the job from a long distance.
Beyond military applications, this device has the potential to improve upon today”s full-body airport screening technologies.
Source: University of Michigan