Hi-Res Scanner Detects 3-D Objects a Kilometer Away

Scientists have been able to detect three-dimensional objects as far as 1 km (1,100 yards) away with an infrared laser scanner system that is largely immune to interference from bad weather and the glare of sunlight.

The imaging system has a resolution at that distance of about one centimeter (0.4 inch) in daylight, according to a team of Dutch and U.K. researchers. They report their result in the current issue of Optics Express, an online publication of The Optical Society.

The new scanner works by sweeping a low-power infrared beam across an object and analyzing the round-trip flight time of individual photons. The infrared system operates at about 1,500 nanometers, which is part of the so-called C-band broadcast spectrum used for long-distance telecommunications.

Other laser scanners can produce higher depth resolution. They use wavelengths less than 1,000 nm and higher power but are susceptible to interference from visible light and are less "eye friendly." The researchers describe their system, which works at sub-milliwatt average power in bright sunlight, as a better compromise of power requirements, range, acquisition time and resolution.

The new system can complete its scan in a few seconds but requires several minutes to process the data. One researcher tells The Engineer that revised software and greater computing power would reduce those times and enable the system to track the speed and direction of moving objects.