Add to that the issue that the scanners produce what is, at best, a poor quality but recognizable "nude" image of the person scanned, and you have to wonder how the UAE customs detected specks of weed and a few poppy seeds.
The true answer was probably more to do with social engineering and expert observation of passengers than technology. UAE customs officers have very frequent and visible patrols in Dubai airport to make those engaged in illicit activities nervous and a ridiculous number of security cameras manned, presumably, by a ridiculous number of officers, continuously watching the crowds.
But today, I suspect that UAE customs have upped their game because what they are most likely now using are terahertz scanners.
Terahertz scanners use terahertz radiation which is interesting stuff. Wikipedia explains:
Terahertz radiation falls in between infrared radiation and microwave radiation in the electromagnetic spectrum, and it shares some properties with each of these. Like infrared and microwave radiation, terahertz radiation travels in a line of sight and is non-ionizing. Like microwave radiation, terahertz radiation can penetrate a wide variety of non-conducting materials. Terahertz radiation can pass through clothing, paper, cardboard, wood, masonry, plastic and ceramics. The penetration depth is typically less than that of microwave radiation. Terahertz radiation has limited penetration through fog and clouds and cannot penetrate liquid water or metal.
Of great relevance to enterprise networking folks:
In May 2012, a team of researchers from the Tokyo Institute of Technology published in Electronics Letters that it had set a new record for wireless data transmission by using T-rays and proposed they be used as bandwidth for data transmission in the future. The team's proof of concept device used a resonant tunneling diode (RTD) [and] sent a signal at 542 GHz, resulting in a data transfer rate of 3Gbps. The demonstration was 20 times faster than the current Wi-Fi standard and doubled the record for data transmission set the previous November. The study suggested that Wi-Fi using the system would be limited to approximately 10 metres (33 feet), but could allow data transmission at up to 100Gbps.
Would that be fast enough wireless for you?
Anyway, one of the many interesting aspects of terahertz radiation is something called "terahertz spectroscopy". One of the leading vendors in terahertz technology, Genia Photonics, offers products in this area and explains:
Sensing science and technology of explosives and related compounds (ERC) are crucial for homeland security and defense-related applications. A wide variety of detection methods are involved in explosive detection including X-rays, infrared, THz, microwave, gamma-rays, etc. The field of terahertz (THz) spectroscopy has been investigated many times over previous years as a technique for the detection of explosive vapour signatures. THz waves can penetrate through many dielectric materials, such as clothing, paper, plastics, leather, wood and ceramics. In addition, THz radiation has low photon energies and will not cause harmful photoionization in biological tissues. Owing to these advantages, THz technology is a competitive method for inspecting explosives carried by a person or concealed in packages. Terahertz radiation lies in the far infrared region from 0.1 to 10 THz. Most explosives and explosive-related compounds have spectral fingerprints within this range and, as many apparatus operate within the range 0.1-5.0 THz.
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