Millimeter wave scanner

Millimeter wave technology

A millimeter wave scanner is a whole body imaging device used for airport security screening. It is one of two common technologies of Full Body Scanner used for body imaging; the other is the backscatter X-ray.

The scanner has been deployed in several countries for security screening.

Technical details

Clothing and other organic materials are translucent in some extremely high frequency (millimeter wave) radio frequency bands. This frequency range is just below the (related) sub-millimeter "Terahertz radiation" (or "T-ray") range.

The millimeter wave is transmitted from two antennas simultaneously as they rotate around the body. The wave energy reflected back from the body or other objects on the body is used to construct a three-dimensional image, which is displayed on a remote monitor for analysis.

Large area operation

According to Farran Technologies, a manufacturer of one model of the millimeter wave scanner, the technology exists to extend the search area to as far as 50 meters beyond the scanning area.

Privacy concerns

See also: Full Body Scanner § Controversies

Privacy advocates are concerned about the use of this technology because it implements routine and, in many cases, mandatory virtual strip searches. It allows screeners to see the surface of the skin under clothing, prosthetics including breast prostheses, and other medical equipment normally hidden, such as colostomy bags.

While the radiation itself cannot distinguish between private and non-private areas, current software imaging technology is sometimes used to mask some part of the bodies of the people who are being scanned. Facial features in the image are blurred before being displayed. Proposed remedies for privacy concerns include only scanning people who are detected to be carrying contraband, or developing technology to mask genitals and other private parts. In some locations, travelers have the choice between the body scan or a traditional "pat down." In other locations, such as the UK, the scans are mandatory.

In the United States, the Transportation Security Administration has claimed to have taken several steps to minimize privacy objections. Governments have claimed that the images captured by the machines are not to be stored anywhere. Despite this and according to CNET News the U.S. Marshals Service admitted that it had saved thousands of images captured from a Florida checkpoint. The screening officer at the machine with the subject does not get to see the image; rather his screen shows only whether or not the actual viewer has confirmed that the passenger has cleared. The officer who views the specific image is in an isolated room away from the security checkpoint, so as to not see the actual person being scanned by the device.

Concerns remain that alternative ways to capture and disseminate the image still exist. Additionally, the identified steps often do not entirely address the underlying privacy concerns. Subjects may be concerned about anyone viewing them in a state of effective undress, even if it is not the visible agent standing next to the machine, or even if the image may not be permanently stored or retrievable.

Possible health effects

Unlike X-rays and UV rays, mm wave photons do not carry enough energy to break chemical bonds or ionize atoms and molecules - they possess even less energy than visible light photons. The human body, due to its natural heat, emits radiation and some scanners operating in the terahertz region rely on this natural emission. It is anticipated that current and future scanners will emit less radiation than is naturally emitted by other sources, however they may still cause some legitimate health concerns.

A study conducted by Boian S. Alexandrov and colleagues at the Center for Nonlinear Studies at Los Alamos National Laboratory in New Mexico performed mathematical models how terahertz fields interact with double-stranded DNA, showing that, even though involved forces seem to be tiny, nonlinear resonances (although much less likely to form than less-powerful common resonances) could allow terahertz waves to "unzip double-stranded DNA, creating bubbles in the double strand that could significantly interfere with processes such as gene expression and DNA replication". However, currently deployed body scanners operate in the millimeter wave region which is below the sub millimeter or Terahertz region that was investigated in this study.

Effectiveness

Some studies bring to question if the cost of the scanners is worth the payback in security benefits. Furthermore El-Al the number one target to terrorists has been operating without body scanners for decades and they have yet to be a victim of terrorist attacks since the 70's. This is due to their rigid questioning by qualified screeners of every passenger without the worry of being politically correct to justify multiple exposure of the public to potentially dangerous radiation. There have been demonstrations to showcase the ineffectiveness of the scanner in its ability to detect any dangerous object a subject may attempt to smuggle though. There has yet to be a report of a successful terrorist capture by a body scanner. However Body scanners have successfully identified individuals smuggling currency, drugs, and other contraband.

Manufacturers

• Smiths Detection
• L-3 Communications
• Brijot Imaging Systems
• Farran Technologies
• Intellifit System
• Thruvision
• Tek84 LLC

Deployment

As of April 2009, the U.S. Transportation Security Administration states that these machines are being deployed at several airports, e.g., at the Los Angeles International Airport (LAX). These machines have also been deployed in the Jersey City PATH train system.

Three security scanners using millimeter waves were put into use at Schiphol Airport in Amsterdam on 15 May 2007, with more expected to be installed later. The passenger's head is masked from the view of the security personnel.

One is currently in use in London Luton airport.

Kelowna International Airport in Kelowna, British Columbia did host the first such device in a Canadian airport. It was pulled from service in 2008 for undisclosed reasons but may have simply been a test unit on loan.

The Canadian Air Transport Security Authority held a trial of the scanners at Kelowna International Airport in 2008. Before the trial, the Office of the Privacy Commissioner of Canada (OPCC) reviewed a preliminary Privacy Impact Assessment and CATSA accepted recommendations from the OPCC. In October 2009, an Assistant Privacy Commissioner, Chantal Bernier, announced that the OPCC had tested the scanning procedure, and the privacy safeguards that CATSA had agreed to would “meet the test for the proper reconciliation of public safety and privacy”. In January 2010, Transport Canada confirmed that 44 scanners had been ordered, to be used in secondary screening at eight Canadian airports. The announcement resulted in controversy concerning whether the scanners constituted too much of an intrusion on privacy, whether they were adequate for security purposes, and whether the exemption for those under 18 would be too large a loophole for terrorists.

Millimeter wave body scanners are also currently in use at Fiumicino Airport, Italy. They will next be deployed in Malpensa Airport.

Other applications

Besides security screening, the scanner can also be used for 3D physical measurement of body shape for applications such as apparel design, prosthetic devices design, ergonomic, entertainment and gaming.

See also

• Full Body Scanner
• Backscatter X-ray (in security scanning applications)
• Puffer Machine
• Security theater