New Year Opens with Terahertz-Scanning Concerns

6. January 2010

By Patricia Daukantas

Like us at OSA headquarters, many of us have now returned to work after the holiday season. Less than two weeks ago, a passenger’s attempt to blow up a jetliner using explosives hidden in his clothing has added a note of worry to what would otherwise be a joyous time.

Because I’ve been following optical research and attending OSA meetings for some years now, every time I heard discussions about airline security and terrorism on the news reports, I started yelling at the TV set: “What about terahertz technology?” What about it, indeed? Known as “millimeter-wave scanning” in the popular press, terahertz-class body scanners and imagers have been a big area of engineering research over the last decade. As Martin Koch noted in a March 2007 OPN feature article about terahertz technology, millimeter waves cannot penetrate more than a few hundred microns into human skin, so they are good at looking through clothing but not at looking into our bodies.

As the editor’s note to an October 2004 OPN article by Kodo Kawase put it: “Until fairly recently, the terahertz range was considered little more than the dark gap that separated the two halves of the electromagnetic spectrum. Now scientists have come to view it as a bridge rife with possibilities for new applications and research.”

If you’re looking for quick explanations of body-scanning technology to give to your non-technical family members and friends, the New York Times and the Washington Post have both published “info graphics” comparing “millimeter-wave” or terahertz imagers to their low-dose X-ray counterparts. An article on the Discovery Channel’s Web site, which was posted just before the Christmas Day terrorism attempt, described recent research into these “T-rays.”

According to Reuters, the U.S. Transportation Security Administration currently operates 40 millimeter-wave scanners at 19 American airports – though that could change. I’m sure that more articles on terahertz body imaging – such as this Times blog entry about the possibility that airport scans might be “pornographic” in some cases – will appear in the media in the days and weeks to come.

Edited on January 6, 2010, to add: Canada is buying 44 full-body scanners to put into its airports, starting with Toronto (the country's busiest airport) and Vancouver (host of the Winter Olympics next month). The Calgary Herald describes them as millimeter-wave devices.

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