Bodyscanners
Monday 29 August 2011
I suppose we have all felt like Loukai Phillips at times as we go through airport security. Loukai was so fed up with being body searched that she decided to take matters into her own hands and stripped naked in front of security staff at Bermuda airport. However many people are now ‘virtually stripped naked’ even though they may not realise it each time they go through a body scanner.
In topic 2.3 the Assessment statement is “Describe the electromagnetic spectrum”. To make this more relevant to students you could describe briefly how body scanners work as there are in fact two main methods in use which use very different regions of the electromagnetic spectrum. One uses ‘back scatter X-rays’. These provide a two-dimensional image by detecting the scatter patterns of the ionising radiation reflected from the body. In airport scanners one image is taken of the front of the passenger and one of the back. The use of image enhancing software enables airport security staff to see a virtual image of the passenger beneath their clothing with the hope that objects such as weapons, explosives and drugs are revealed. Although X-rays are used it is claimed that the dose received by the passenger is less than that received during two minutes of flying and is virtually harmless.
The second type of body scanner uses even less harmful rays. These are known as millimetre wavescanners and may be passive or active. Both use radiation in the radio frequency (just below the tetrahertz region where the wavelength is between 0.10 mm and 1.0 mm). Passive scanners record only the raw energy that is emitted from the body (or concealed objects) and direct no energy at the passenger. In active scanners the radiation is transmitted from two antennae as they rotate around the body. This is the system in use at Schipol Airport in Amsterdam and some other EU airports. Like the back scatter X-ray system it allows screeners to see the surface of the skin beneath the clothing. Some individuals and organisations have complained that it is a breach of privacy and in the case of passengers under the age of 18 there is concern that it could contravening the UK Children’s Act by producing indecent images of minors.
