[Paleopsych] NYT: Using Advanced Physics to Find Concealed Weapons

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Using Advanced Physics to Find Concealed Weapons
April 14, 2005


    Three companies are racing to market a new form of technology for
    detecting concealed weapons, using physics borrowed from radio
    astronomy and manufacturing techniques from cellular phone makers.

    The technology, called millimeter wave, is a new category of sensing
    so unobtrusive that it seems like something out of "Star Trek."

    Unlike conventional systems such as metal detectors, which sense
    magnetic fields created by certain materials or objects, or X-ray
    machines, which pass rays through objects, millimeter wave sensors are
    passive and rely on detecting energy emitted by objects.

    The energy the sensors look for is in an unfamiliar part of the
    electromagnetic spectrum, different from the usual visible light or
    infrared. At wavelengths of two centimeters to one millimeter, the
    energy is much longer than light or infrared waves, and thus able to
    pass through clothing and similar material. Human bodies radiate the
    energy at a rate higher than metal, plastic or composite materials, so
    those objects can be spotted under clothing, in silhouette.

    The sensors have been successfully demonstrated in laboratories and
    have been sold mostly to government agencies for evaluation.

    With research grants from the National Institute of Justice, the
    technology arm of the Justice Department, and from the Defense
    Department and other federal agencies, three small firms - Brijot
    Imaging Systems, Millivision Technologies and Trex Enterprises - are
    working to manufacture portable sensor units.

    "Millimeter wave imagery is remarkably well understood, but no one's
    been able to build anything cheap enough and small enough to be
    practical," said Brian Andrews, president and chief executive of
    Brijot Imaging, which is a partner with Lockheed Martin, the giant

    Mr. Andrews says his company has done just that, with a $60,000 box
    that is supposed to be able to see from 5 to 45 feet, depending on the
    lens attached. A computer scans the images and looks for anomalies
    that could be weapons.

    A second company, Trex Enterprises of San Diego, has a unit that sells
    for $50,000 (so far only to government customers), and is working on a
    hand-held version. Its chief technology officer, John A. Lovberg,
    compared the technology to infrared technology, which is also
    "passive," meaning that the sensor measures natural emissions rather
    than bouncing energy off the object being observed, as radar does.
    Infrared is used in a variety of settings, including military

    Mr. Lovberg said that the technology mounted on cars or planes could
    also help drivers or pilots see through fog or smoke. Millimeter wave
    sensors, he said, can show "the difference between a road and a tree
    and a metal street sign."

    Millivision, of South Deerfield, Mass., is marketing a detector about
    the size and shape of telescopes used by serious amateurs. The company
    is partly owned by L-3 Communications, a major manufacturer of
    scanning equipment. The potential market, said William J. Caragol,
    vice president for business development, is "any entrance that you
    pass through where there's a need for security."

    "It expands," he said, "to every office building, stadiums - fill in
    the blank."

    Millivision has a $60,000 device it has sold to government agencies
    for testing, Mr. Cargol said. With L-3, it is developing a portal with
    controlled-temperature conditions, for more accurate scanning. The
    Millivision sensor, he said, can spot a ceramic gun that a metal
    detector would miss.

    The Justice Department expects to use the sensors as security tools
    for courthouses and other buildings, but says they could also have
    commercial applications.

    Over the last eight years, the department has given about $7 million
    in research grants to companies working on millimeter wave
    technologies. Sara V. Hart, director of the National Institute of
    Justice, said in an e-mail message: "We want law enforcement and
    corrections officers to be able to detect any weapon, such as a bomb,
    gun, knife or nonmetallic weapon, from a safe distance. This would
    enable officers to make immediate protection decisions to protect
    themselves and the public."

    She said that the technology could be "practical for use within the
    next few years" and that her agency had bought several systems for

    The energy levels detected by millimeter wave sensors are extremely
    small - mere whispers of energy measured in femto-joules, or
    quadrillionths of a joule. (A joule is the amount of energy of one
    watt applied for one second.) Chips, which are used in the sensors to
    process the data and run at speeds similar to the frequencies
    involved, 80 to 100 gigahertz, are still quite costly to make. But the
    machines that manufacture the chips have gotten cheaper because they
    are closely related to the machines that make chips for cellphones.

    Mr. Lovberg of Trex said that advances in electronics are making
    millimeter wave technology more affordable. "Ten years ago, you
    couldn't buy amplifiers in this spectrum," he said of the amplifiers
    used in the sensors. But semiconductors made of gallium arsenide or
    indium phosphide can run in the frequencies required, he said. Those
    chips have been commercialized for use in other devices, and are now
    available for use in millimeter wave technology.

    Tom Byrne, a member of the executive board of the Center for
    Commercialization of Advanced Technology, a public-private consortium
    in San Diego that provided a $75,000 grant to Trex, said, "In the past
    there was a lot of expense in the receiver because the signal is a
    low-grade, weak signal, and that pushed the price up." But now, the
    receivers are getting more sensitive, Mr. Byrne said, and that is
    reducing the price and making the sensors potentially viable.

    Some companies are working on "active" millimeter wave systems, which
    are more like radar in bouncing energy off the person being studied,
    Mr. Byrne said. In fact, low-power radar is already in use at some
    airports to search arriving passengers. But radar systems raise
    potential health concerns from exposure to the energy, and also
    privacy issues because body parts are clearly visible. Active
    millimeter systems could raise the same worries.

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