X-rays , which run a bit larger, have a wavelength on the order of 0. And visible light waves measure about 0. The entire collection of waves, across all frequencies, is known as the electromagnetic spectrum. Now consider a wave that falls in a range exactly between 0.
Scientists refer to the energy in this tiny sliver of the electromagnetic spectrum as millimeter wave radiation. Millimeter waves have a variety of uses but are especially important in radio broadcasting and cell phone transmissions. And, because the wavelengths of millimeter waves are large relative to natural and synthetic fibers, they tend to pass through most materials, such as clothing, making them an ideal candidate for scanning technologies.
Millimeter wave scanners produce their waves with a series of small, disc-like transmitters stacked on one another like vertebrae in a spine. A single machine contains two of these stacks, each surrounded by a curved protective shell known as a radome , connected by a bar that pivots around a central point. Each transmitter emits a pulse of energy, which travels as a wave to a person standing in the machine, passes through the person's clothes, reflects off the person's skin or concealed solid and liquid objects and then travels back, where the transmitter, now acting like a receiver, detects the signal.
It's the job of software in the scanner system to interpret the data and present an image to the TSA operator. The software creates a 3-D, black-and-white, whole-body silhouette of the subject. It also employs a feature known as automated target recognition , or ATR , which means it can detect threats and highlight them for easy identification. ATR technology is capable of detecting liquids, gels, plastics, powders, metals and ceramics, as well as standard and homemade explosives, drugs and money.
The ATR software also does something else. A scanner without this software forms images that reveal a person's unique topography, but in a way that looks like a crudely formed graphite prototype.
In other words, you can see some physical features, but not with the same detail as Superman or backscatter scanners , both of which possess X-ray vision. A millimeter wave scanner with ATR software produces a generic outline of a person -- exactly the same for everyone -- highlighting any areas that may require additional screening. Millimeter wave scanners aren't metal detectors.
They actually peer through clothing to look for metallic and nonmetallic objects an individual might be trying to conceal. Getting a good view requires that passengers entering the scanner follow certain procedures. Here's what you can expect if you enter one of the approximately mmw scanners in use at airports across the U. Either way, the scan takes less than 10 seconds and requires nothing painful or embarrassing.
But if you feel strongly that the whole-body scan of a millimeter-wave machine violates your privacy, you can opt out of the screening process. You will, however, receive alternative screening, including a physical pat-down. According to the TSA, most people prefer the scanning process to a physical exam.
In fact, more than 99 percent of passengers choose to be screened by this technology over alternative screening procedures [sources: TSA]. And people with artificial joints or other implanted medical devices appreciate mmw scanners even more because they don't have to worry about the false positives associated with old-fashioned metal detectors. As soon as the TSA began installing millimeter wave scanners, the public began asking questions, mostly related to privacy and safety.
In the former category, people objected to the idea of strangers peering beneath their clothes to see intimate details or reveal evidence of mastectomies, colostomy appliances, penile implants and catheter tubes. A representative of the American Civil Liberties Union described whole-body imaging as "nothing more than an electronic strip search.
To quell the uproar, the TSA introduced several precautions on mmw scanners. One of those, as we've already discussed, involves installing automated target recognition software on a number of the machines.
The software renders every subject as a generic outline, with suspicious areas highlighted. And if it doesn't detect anything suspicious in a scan, it displays the word "OK" with no image at all. For scanners without ATR software, the security operator viewing the resulting image sits at a remote location and communicates wirelessly with the agent operating the machine.
And no machine is capable of storing images. Each image is deleted automatically as soon as the remote security officer completes his or her inspection. That said, what's a rule without an exception? The U. Marshals Service failed to delete thousands of images captured with a millimeter wave system at a courthouse in Florida. Yep, thousands [source: McCullagh ].
Of course, none of these measures protects a passenger from harmful effects of the waves themselves. Luckily, several studies have determined that millimeter wave scanners pose little risk to passengers, pilots or the TSA agents who operate the machines.
The waves produced by these scanners are much larger than X-rays and are of the non-ionizing variety. Ionizing radiation has enough energy to remove electrons from atoms, but radio waves, visible light and microwaves don't have this ability. But what are these scanners? How do they work, how do they differ from one another, and more importantly, are they dangerous to our health?
Backscatter X-ray scanners and millimeter wave scanners are both full body scanners used in the screening area of airports across the world. They are used as a secondary screening tool, giving passengers selected for a secondary screening an alternative to a physical search.
They both create an image by sending low-level waves, or rays towards your body, and detecting the waves which scatter, or bounce off the surface of your body, as well as any objects next to it. The purpose is to reveal any objects someone is carrying under their clothes, particularly liquid explosives, weapons, and drugs.
Millimeter wave scanners are the only type of full body scanner used in Canada. For information about those, go here. Only one person at a time can do this, so your child cannot be in the screener with you because no clear image will be created. We realise that the process can be challenging for parents and children, so we have a number of ways to carry out appropriate security checks to make this as easy as possible for you and your family 4.
By the way, children who are shorter than 1. A security officer — who has also been especially trained to do this — will give you a pat-down search and will also have a quick look at any of your mobility aids. Because the scanner is designed to identify objects carried on the body, it is possible that prosthetic limbs will trigger an alert. The security officer will investigate and resolve any such alert. Every security officer involved in this procedure knows the rules, and importance, of being courteous.
You can hold us to that. There are no known safety worries if you have implanted medical devices like pacemakers or defibrillators 5. If the body scanner does detect an object and indicates where it is on the image on the screen, the security officer will conduct a pat-down search of the area indicated.
You can see the image as you step out of the scanner. Occasionally, the system may indicate something to be investigated which is actually innocuous 6. The software is being continually improved with the aim of delivering far fewer false indications. There are no known health risks from undergoing a scan, so passengers who have a medical condition or are pregnant should not be worried.
Firstly, images are displayed as a vague genderless figure. The advantage of that to the security officer is that areas they might need to further investigate are clearly highlighted. The advantage to you and your privacy is that your identity, even your gender, is anonymous to that security officer. For more information about body scanners, go here. You are here Home About us News and media releases Our new body scanners explained — protecting you and your privacy More About us Contact us Change of address Contact the aviation safety group Official Information Act request Personal information request Questions, complaints, and feedback Report a drone safety concern Report an aviation safety concern.
Aviation security legislative framework How we are funded Fees, levies, and charges Previous funding reviews Review of CAA fees, levies, and charges suspended Questions and answers. About our dogs Behavioural detection Security screening and other airport duties Supporting other government agencies.
0コメント