Researchers have designed a camera that can capture microwave images using a single-pixel sensor and produce ready-compressed data. The system, described last week in Science1, could be adapted for other wavelengths, such as those used in millimetre-wave scanners for airport security screening.Today's cameras take images as 'raw' arrays of pixels, which can take up many megabytes of storage, and then use data-compression algorithms such as JPEG to store the image in a smaller file.
"Why collect that data in the first place?" asks John Hunt, an engineer at Duke University in Durham, North Carolina, and a co-author of the study. To design the new device, Hunt and his colleagues used an approach called compressive sensing.The trick is figuring out what data to acquire, says Richard Baraniuk, an electrical and computer engineer at Rice University in Houston, Texas. "The data-points that matter will be different in a picture of the Eiffel Tower and a picture of your mother," he says.
But it is not possible for a device to 'know' what is important before the data are recorded. Compressive sensing works by sampling at random — eliminating the need to sift through data — and it still produces enough information to generate a good image.For the latest study, the researchers turned to metamaterials — artificial structures patterned to interact with light in exotic ways. Whereas a conventional microwave radar system uses a moving dish antenna to collect microwaves reflecting off a moving object, the Duke system uses a stationary metamaterial aperture, a strip that guides microwaves to a single sensor.
No comments:
Post a Comment