Light Trick
Simpler microwave imaging
A fast, simple microwave imaging system that involves no lens.
The days of standing still, arms raised, in an airport security scanner may soon be a thing of the past. A new microwave imaging system offers a fast, inexpensive way to see through clothing and other objects that gathers data without involving complicated moving parts. The new system, reported in the Jan. 18 Science, employs a thin copper strip as an aperture that collects a range of microwave-frequency light. Elegant math then converts those data into an image in less than a second. “This definitely represents a less expensive and potentially faster alternative to current imaging methods,†says technologist Kevin Kelly of Rice University in Houston, who was not involved in the research. “You can imagine an MRI or PET scanner where instead of sitting in a machine for 50 minutes you sit in it for five minutes.†In a digital camera, the lens focuses light onto an array of pixels on a detector. If you want a million-pixel image, you essentially need a million detectors, says John Hunt, a Duke University physicist who led the new work. That many-pixel, many-detector approach doesn't work with microwaves, which are longer than waves in the visible part of the electromagnetic spectrum. So microwave imagers used in car collision avoidance systems for their ability to see through fog and rain have a single detector that must be slowly moved across a plane with the help of complicated, expensive gears.
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