Airport 3d body scanner

What Do Airport Body Scanners Really See? Can They See You Naked?

Sure, airport body scanners are looking for threats, but here’s what else these security devices might reveal in the process

Some of us remember when friends and family could walk you to your gate and you could board an airplane without a detailed airport security check. Now, of course, you have to worry about the TSA carry-on rules—including the liquid limit and food rules—and figure out what to pack in your checked luggage instead. And then there are the metal detectors, facial scanners and body scanners. You know those machines are there for your safety, but they still may give you pause—especially the body scanner. After all, what does it show, exactly? Can TSA agents see you naked?

Those are valid questions. You might also be wondering if body scanners are safe and if you can skip them if you sign up for Global Entry or TSA Pre-Check. We spoke to TSA experts to get the lowdown on airport body scanners so you know exactly what to expect the next time you head to the airport.

How do body scanners work?

Before we answer the question of what body scanners see, we need to discuss how they work. What happens when you step into the machine, place your feet on the footprints and put your arms over your head? “Body scanners use a technology called Advanced Imaging Technology (AIT) for full-body scans at airport checkpoints,” explains TSA spokesperson R. Carter Langston. “It’s a millimeter wave scanner that detects a wide range of metallic and nonmetallic threats in a matter of seconds.”

While there’s a lot of complicated science behind that millimeter wave imaging, here’s the gist: “Essentially, the machines send millimeter waves toward a passenger’s insides,” explains Shawna Malvini Redden, PhD, the author of 101 Pat-Downs and a communication researcher who has studied the TSA since 2010. “The waves go through clothing and reflect off the passenger’s skin (and whatever else is concealed) and bounce back an image, which is interpreted by the machine. ”

If the electromagnetic waves hit something that seems suspect, a Transportation Security Officer (TSO) will investigate further. But if not, says Langston, you can pass right through the security checkpoint without a pat-down or other physical contact. Have something you shouldn’t? Here’s what happens to items confiscated by the TSA.

What do body scanners see?

Body scanners are looking for items that could be potential threats; they’re not looking at your physical body. The TSOs see “a generic human form—or avatar—to ensure passenger privacy while maintaining security effectiveness,” Langston says. This looks kind of like a gingerbread man or paper doll.

“With millimeter wave machines that have the privacy software installed, TSOs are only seeing this outline with a green ‘clear’ or a red ‘stop and check’ signal,” Malvini Redden explains. “If someone has something in their pockets, for instance, the machine will put an alarm note in the paper doll’s groin region so the officer knows generally where to search. ”

Do airport body scanners see you naked?

aviation-images.com/getty images

According to the TSA, a body scanner doesn’t show your naked body on its screen … anymore. “Early versions of the scanners came out without any privacy protections, and TSOs in the checkpoint could be looking at naked images of passengers as they went through the screening,” explains Malvini Redden. These scanners used backscatter technology, but because of privacy and health concerns, those machines were removed from all airports in 2013. “Now when passengers are scanned, the machines are supposed to generate generic images of a body instead of the passenger’s unique image.”

Millimeter wave machines don’t see nipples or genitalia, and they do not pick up size, weight or height. Can you see a tampon during an airport body scan? This is a frequently asked question on Google, and if it’s something you’re worried about, you can breathe a sigh of relief. Airport body scanners can’t see inside the body and therefore can’t detect a tampon on a TSA female body scan image. “Millimeter wave imaging technology does not detect items inside a passenger’s body or penetrate the skin,” Langston says.

That said, Malvini Redden says body scanners would also not pick up anything else stashed inside a body cavity, such as drugs or hazardous liquids. These items might be detected, however, if they were in your pockets. In case you were wondering, you might have to go through a body scanner again if you’ve left the airport during a layover, but not if you’re simply getting a connecting flight.

What are airport body scanners looking for?

Airport body scanners alert the TSO to threats—mainly weapons such as knives, guns and explosives. They are designed to detect “metallic and nonmetallic threat items,” according to the TSA. Those are things like explosives or knives made out of materials other than metal, like ceramics, says Malvini Redden.

That said, “benign undivested items” may also be picked up by the AIT, which is why it’s worth thinking about what you wear on a plane. What are benign undivested items? Those are the things we’re supposed to put in the bins before walking through security checkpoints but accidentally forget about. Think watches, keys, belts, coins, jewelry, IDs, phones and the like.

What might accidentally set off a body scanner?

Aside from the items you’ve forgotten to put in the bin, there are a few unusual things that can cause a body scanner to come back with that dreaded red signal. The TSA declined to respond to this question, but according to Malvini Redden, the most contentious trigger is thick hair, especially if it’s in a braid or a bun and if there are clips holding it. Other things that accidentally set off body scanners are body piercings and wire supports in undergarments. External tumors might also trigger the machine, but growths inside—such as fibroids—will not.

“Perspiration is probably the weirdest thing that can set off the scanners,” Malvini Redden says. “It has to do with millimeter wave technology and how the waves bounce off water.” She adds that since these machines often generate false alarms like this, some countries (including France and Germany) have banned them.

Do body scanners really work?

According to the TSA, body scanners are effective at spotting weapons. “It is a proven technology, and we are highly confident in its detection capability,” Langston says. “It has been widely accepted as an alternative to the full-body pat-down, which remains the alternative security screening protocol for those who refuse full-body security scanners.”

Malvini Redden notes, however, that they’re not infallible. The machines can malfunction, the alarms can go off without good reason, and they’re cumbersome and expensive. In short, she says, they “work to portray the appearance of taking security seriously,” but she questions just how effectively they actually do that.

Can you refuse to go through a body scanner?

Yes, you can refuse to go through an airport body scanner. Still, you should always be polite about it—the machines are there for your safety—and be mindful of the things you shouldn’t say to a TSO that might get you flagged as a disruptive or unruly passenger. (These things are similar to what you shouldn’t say to a flight attendant, FYI.)

Just be aware, says Malvini Redden, that if you opt out, “a TSO will physically check your body from head to toe, possibly including an intimate check of breasts/groin/buttocks.” You can request a private room for the screening, but they’re typically done near the checkpoint.

While you can sign up for a TSA PreCheck to skip some of the more onerous security processes like taking off your shoes, removing liquids from your carry-on and taking your laptop out of your bag, you’ll still have to go through the body scanner, according to Langston. But, says Malvini Redden, some checkpoints may direct you to the regular metal detector instead.

Are full-body scanners safe?

Between 2009 and 2013, the TSA used Rapiscan backscatter machines, but there were concerns about safety (in addition to privacy and effectiveness). They produced a stream of low-energy X-rays, which people worried could increase radiation exposure.

The newer AIT scanners, however, use millimeter wave imaging, which is a special type of microwave, not an X-ray. In fact, we’re exposed to this type of non-ionizing radiation every day at low levels, according to the CDC. When exposure is too high, a person may experience tissue damage (for example, a sunburn on a tanning bed), but it’s nowhere near as problematic as the ionizing radiation used once upon a time in airport body scanners.

Still, those who fly often may not want to be exposed to this on a daily basis, and that was doubly true when the Rapiscan machines were being used. In 2010, pilot and flight crew unions successfully lobbied to change the requirements to go through advanced imaging and avoid the excess radiation, says Malvini Redden. Flight attendants followed suit in 2012.

Should regular fliers—even frequent fliers—be concerned today? Nope. “Passengers don’t have anything to worry about. The AIT scanners are safe,” Langston says. “And the energy emitted by millimeter wave technology is 10,000 times less than what is permitted by the standard cellphone.”

Sources:

R. Carter Langston, TSA spokesperson
Shawna Malvini Redden, PhD, professor and communication researcher and the author of 101 Pat-Downs
U.S. Immigration and Customs Enforcement: “‘Underwear Bomber’ Umar Farouk Abdulmutallab sentenced to life”
CNN: “TSA removes body scanners criticized as too revealing”
How Stuff Works: “How Millimeter Wave Scanners Work”
ProPublica: “Sweating Bullets: Body Scanners Can See Perspiration as a Potential Weapon”

3D body scanners at Australian airports: what are they and how do they work? | Transport

Sydney airport has just begun using 3D body computed tomography scanners in its Qantas domestic terminal, T3. Though CT scanners have been widely used in international terminals in Australia for several years, and are in place in Melbourne’s T4 terminal and at Gladstone and Canberra airports, it is the first time many passengers have seen the technology at a domestic airport.

What are the scanners, and how do they work?

They are large tubes that passengers are asked to enter, before raising their arms while the machine rotates around them. They use nonionising millimetre-wave imaging to scan a person, looking for anything they may be carrying under their clothing. They are capable of detecting metallic and non-metallic items.

Airport security staff are presented with a generic cartoon outline of a person, with areas of interest highlighted in square boxes. Melbourne airport says no individual scans or personal information is stored or transmitted by the scanners.

CT scanners are also used for carry-on luggage.

Why are they being brought in?

In 2018 the then home affairs minister, Peter Dutton, announced that airports would be required to shift from using metal detectors, with budget funding earmarked for regional airports.

This came the year after two brothers plotted to blow up a passenger plane with a bomb hidden in a meat grinder.

“We’re worried about different devices going through the scanner that wouldn’t be picked up at the moment,” Dutton told the Melbourne radio station 3AW in 2018. “We’re worried about gels. We’re worried about noxious gases, all sorts of things which potentially don’t get picked up.”

Dutton said the new scanners would be rolled out “over the next couple of years” but it has taken four years for one checkpoint in one terminal of Australia’s busiest domestic airport to get the technology.

Guardian Australia understands the other checkpoints in T3 in Sydney will be upgraded with the same technology by the end of the year.

How much is it costing?

The Australian Airports Association estimates the cost of the upgrade is $2bn. In a pre-budget submission this year, it said the size, scope and scale of the upgrade, along with the pandemic’s effect on the airline industry, had made the project more complex for the 10 largest airports in Australia, and called for federal government funding to offset the cost.

Will they make going through airport security faster?

In theory, yes. CT scanning means passengers will no longer have to remove laptops, aerosols and other items from their carry-on luggage at security checkpoints. But they will still need to remove jackets and other outerwear.

Last week the ABC reporter Louise Milligan tweeted her experience of being required to remove a fitted jacket and said others had complained about security “heavy-handedness”.

Sydney airport declined to comment but the security contractor, Certis Security, told Guardian Australia the removal of coats and jackets was a requirement and referred inquiries to the regulator, the Cyber and Infrastructure Security Centre.

In practice, delays are still likely at airports given ongoing staffing shortages, so the scanners are not likely to shave off any time for quite a while.

Can I refuse to go through one?

Though exceptions are made for people who have medical or physical conditions that prevent them from going through body scanners, airports will refuse to let you enter the terminal if you do not comply.

New 3D scanner at airports could make life easier for passengers

July 24, 2018

Image credit: WPA Pool

London's Heathrow Airport is testing technology that could drastically simplify baggage rules around the world in the near future.

Thanks to special scanners, passengers do not have to remove liquids from their hand luggage.

Up to view from all sides

As part of the experiment, 3D scanners were installed at Heathrow, which work on the principle of a CT scanner.

Their beams allow you to get an accurate image of the contents of hand luggage and view objects from any angle. In addition, scanners are able to detect explosives hidden in luggage.

This technology has been used by medical professionals for many years to obtain images of internal organs. It is also used at airports to inspect suitcases that are transported in the luggage compartment.

"If tests are successful in the future, passengers will not have to remove items from their baggage for screening," the UK Department for Transport said in a statement.

Passengers are now required to present laptops during screening at airports, as well as take out restricted liquids.

The experiment will last for several months.

Similar scanners were installed and tested at the New York airport. Kennedy, as well as at the airports of Geneva and Amsterdam.

During the tests, some passengers may not unpack their bags during the tests. True, security officers may at any time require you to show the contents of your luggage.

R Carrying liquids

Photo credit, Photofusion

Caption to photo,

Now many passengers are forced to stay for a long time in the security checkpoint, removing liquids from their suitcases

Some experts believe that technology can simplify the rules of transportation liquids.

The current regulations were established in 2006 throughout the EU and extended to other countries.

According to them, containers cannot exceed 100 ml, and all of them must be packed in a transparent bag with a volume of no more than one liter.

The ban came after British intelligence agencies announced in August 2006 that they had prevented a series of terrorist attacks on board ten aircraft from Heathrow.

The terrorists were going to blow up the airliners in the air using liquid explosives, the components of which they planned to carry on board under the guise of drinks.

The scanners that the security services have begun testing could lead to a complete abolition of such restrictions, Philip Baum, editor of Aviation Security magazine, told the Sunday Times: "This is the end of the liquid ban, a decision long overdue."

Representatives of the European Commission said five years ago that restrictions on the carriage of luggage could be lifted thanks to new technologies for screening passengers.

Due to restrictions, screening procedures at airports have been seriously lengthened.

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Development of personal screening systems. Inspection equipment. Master Class. SPETSINTEK LLC

How to improve air traffic safety without disturbing passengers with a large number of checks?
The innovative security scanner QPS100/QPS200 will help with this.

The typical air traveler has mixed feelings about safety. According to a survey presented by the German Federal Association for Information Technology, Telecommunications and Media (Bitkom), the majority of passengers approve of the widespread use of airport security technologies, including scanners. At the same time, they are annoyed by many inconveniences, ranging from luggage restrictions and the need to remove various items of clothing during security checks, to the unnatural position required by conventional body scanners and being searched by security personnel. And this is only exacerbated by the long wait at the checkpoints. With security standards unlikely to be relaxed any time soon, technology faces a new challenge to find a solution to this problem despite even tighter security measures.

Figure 1. The dual-panel QPS200 is designed primarily for airport use. It can be integrated into almost any security checkpoint. The QPS100 model consists of one flat panel, therefore, for a full inspection, a person is sanitized twice - in front and behind.

The goal is to maintain the highest level of safety while maintaining the greatest possible comfort for passengers. The new body scanner R&S QPS200 is an important step in this direction.

New product launched

The first scanners were developed in the early 1990s, before there was a significant market for them. These X-ray backscattering devices were used at airports. Microwave devices followed a few years later, although demand remained limited. After the dramatic events of September 11, it became clear that the market for security equipment would develop rapidly. As a result, Rohde & Schwarz very quickly decided in 2007 to become a partner in a consortium working on a project to offer a European alternative to products from the United States that were pioneers in this category. A three-year proof-of-concept research and development phase has concluded, which has validated the consortium's path. However, the divergent concepts of the serial production model have forced the participating partners in the industry to develop their own, separate paths. Within QPASS, a project initiated by Rohde & Schwarz and funded by the German Federal Ministry of Education and Research followed. Rohde & Schwarz, together with the Institute for Microwaves and Photonics at the University of Erlangen-Nuremberg, Germany, has been working to prepare for the production of a prototype that has shown the potential to meet all expectations, even as new EU requirements pose additional challenges.

In the past, devices were designed to create images that could then be evaluated by screeners. The fact that intimate details were also visible sparked an emotionally charged public debate that forced US and European authorities to change their rules. It is now forbidden to display photo images at checkpoints. Apparently, this is a simple regulation, but with extremely serious technical consequences. Now the task was to develop a method for automatically detecting suspicious objects. This required extending the millimeter wave technology with a fast imaging system that could reliably filter out anomalies from the measured data for display (Fig. 2). The development team assembled for this challenge made such rapid progress that the QPS100 production model was ready for deployment in 2014. Field tested, continuously improved, with all applicable certifications and expanded to include the QPS200, the R&S QPS platform today serves as an innovative security solution not only for airports, but for all areas requiring a high level of security and limited access. Demand is high. Countries such as Germany are following the example of the United States, which in 2010 began to consistently equip all airports with scanners. With the signing in July 2016 of the Agreement between the German Federal Ministry of the Interior and Rohde & Schwarz for the supply of 300 units, the R&S QPS200 is well on its way to becoming the standard equipment in German airports.

Figure 2. The scan result is displayed on a neutral graph. Personal data is not displayed or stored.

A Brief History of Airport Security Reviews

The history of airport security, at least as far as defense against attacks, is linked to a series of key events and responses to those events. In the early decades of commercial aviation, airport security was essentially non-existent, as flying was an exclusive adventure that only wealthy clients could afford, and far from the stage of violent crime requiring protective measures. Even when there was air piracy, mostly politically motivated, with a record 82 hijackings in 1969, the authorities still did not see the need for significant countermeasures. Metal detectors were only used when examining passengers when there were grounds for suspicion. It wasn't until the 1980s, when the US in particular intensified its war on drugs, that passenger screening was stepped up and service dogs were brought into play. In 1988, the Lockerbie bombings resulted in some baggage being scanned in Europe; However, it was not until 2003 that checking every piece of baggage became mandatory under EU regulations.

In many ways, the attacks of September 11, 2001 represented "time to go" in terms of security policy. Every possible level of government has done everything possible to prevent re-attacks, from extensive cross-border reconciliation of passenger data to air marshals, to a ban on the transport of sharp or sharp objects such as nail files in hand luggage (The installation of such equipment cost only for Lufthansa alone, more than 30 million euros according to company statements). As a result, from this point on, there have been dramatic changes in the security check before boarding. Richard Reid's attempt in December 2001 to detonate explosives hidden in the heel of his shoes was thwarted, but the US and several other countries responded by requiring passengers to remove their shoes for inspection. A ban on large volumes of liquids was further introduced in 2006 after a plan to use liquid chemicals in an attack was revealed in the UK. During Christmas 20091999, terrorist creativity even extended to underwear when a Nigerian citizen tried to detonate explosives hidden in his underwear shortly before landing in Detroit. The Transportation Security Administration, set up in the US in response to 9/11, responded to the attempt by introducing full-body scanners at airports across the country. The installation of these devices, which were developed in the 1990s, began in 2007 at airports in the United States and other countries and cities such as Amsterdam, but their widespread use began in 2010. This first generation of scanners was based on X-ray technology, which made visible not only potentially dangerous objects, but also private parts of the body, leading to significant public criticism. In addition, X-rays have an ionizing effect and therefore cause damage to cells, even though the authorities rule out any health hazard due to the low level of radiation from the devices (measurements show that the level experienced by passengers is approximately equal to a few minutes of cosmic radiation). However, these backscatter devices have largely disappeared from the market and are now banned in many countries. Even the Transportation Security Administration took the big decision to eliminate all first-generation devices between fall 2012 and May 2013, replacing them with alternative millimeter wave technology. However, this move was not made for public health reasons, but rather because the device manufacturer failed to implement a software update in time, in which the scan results would be impersonal. In response to public outcry, US authorities included a provision in the Modernization and Reformation Act of 2012 that nude images created by body scanners should be replaced with a symbolic image of the body, identical for all subjects.

For health reasons, the European Union banned the use of X-ray scanners (and all technologies that use ionizing radiation) in a regulation that came into force in November 2011. The retention of personal data and data protection rights is also mandatory. Germany conducted the first test of the first generation mmWave scanner in 2010 at Hamburg Airport. Field trials were carried out and scientifically supported by the center of the German Federal Police. 800,000 volunteers, including the German Federal Interior Minister de Maizière, gave permission for the scan. The purpose of the large-scale test was to determine how the devices would perform in real life, to identify any problem areas and to figure out how to optimally implement common testing methods. National authorities work directly with the European Civil Aviation Conference (ECAC), which is responsible for air transport-related certification, and the Hamburg test has played a pioneering role here. The test results (including a high false alarm rate) have led the German federal government to conclude that the devices currently available on the market are not yet suitable for general use. Since then, manufacturers have stepped up efforts to improve reliability.

Latest generation scanners such as Rohde & Schwarz's QPS are smarter than their predecessors and suitable for unlimited and widespread use. Regulators also require scanners to speed up security checks rather than slow them down. The fast devices currently available make this possible. The increased use of automated safety equipment gives reasonable hope that the perceived burden on passengers will be reduced to an acceptable degree in the near future. The first step in this direction was the complete removal in the EU of the ban on large volumes of liquids in hand luggage in 2014 (although restrictions on medicines, special products and goods purchased in the duty free zone remained). This was made possible thanks to new technology that allows the detection of liquid explosives. Advances in scanning technology will soon allow screening through thick layers of clothing so that passengers no longer need to take off their coats and jackets. Solutions invisible to the eye are already on the horizon, meaning passengers will be subject to security checks without even noticing it. It is hoped that travelers will be able to board the plane without issue, unlike the woman who had her Christmas cake confiscated in Las Vegas because a security guard thought the icing looked too much like explosives.

New approaches

The QPS Scanner differs from competing products in the way it looks, how it works and how it scans. Vast spaces with bulky stands are a thing of the past. Visually appealing, compact, flat panels can be integrated barrier-free into a checkpoint (Figure 1). The open design gives security personnel an unobstructed view of the entire checkpoint. The scanning procedure, which is considered unpleasant due to traditional equipment, since passengers must keep their hands in the air, as if they were stopped by the police, is now much more comfortable for passengers. You need to slightly spread your arms in a natural position, which is possible even for physically weakened people, and is considered ethical in different cultures.

The QPS Scanner is a completely electronic, low noise instrument with no moving parts. It is the only device on the market that is based on the multi-static principle familiar from radar technology, where the reflected transmitted signal is applied simultaneously to a large number of receiving antennas (Figure 3). This provides better illumination of the scanned person, resulting in improved detection quality.

Figure 3. Multi-Static Operation: While only one of the 3008 transmitters is active in the panel, all 3008 receive antennas receive the reflected signal. Since each transmitter also quickly passes through 128 frequencies before the next one starts transmitting, each scan cycle transmits over a billion (!) complex values to the panel (amplitude and phase), in less than 32 ms.

Apart from a calibration check every six months, the system is virtually maintenance free. Of course, these checks are carried out on the spot. Installation and commissioning take less than an hour, because all the preliminary labor-intensive processes are carried out at the factory.

Conventional microwave scanners illuminate objects at frequencies below 30 GHz. The R&S QPS, in contrast, achieves higher spatial resolution as it operates in the millimeter wave band between 70 GHz and 80 GHz, a band also used by vehicle parking sensors. At about 1 mW, the peak transmit power is about three times lower than that of mobile phone emissions and is hardly detectable where the person being scanned is standing.

Scanning volume - 1.9 mm × 1.9 mm × 5.7 mm voxels, which is achieved not only due to the high frequency range, but also due to the multistatic principle of operation. It was difficult to implement this in a high resolution, close range scanner. To make a multistatic mmWave scanner workable, its surface must be completely covered by antennas, which means placing a quarter of a million antennas on a panel for an R&S QPS size scanner. It took years of fundamental research in an attempt to reduce the number of antennas within reasonable limits, and this became the basis for more than one doctoral dissertation. As a result, a design was developed, consisting of 3008 transmitters and 3008 receivers, distributed in 32 clusters on each panel in a checkerboard pattern (Fig. 4). In addition to transmitters and receivers, the clusters contain the electronics required for frequency processing and conversion. The received signals are downconverted to 25 MHz and the signals from the four clusters are received to one of the eight IF modules located behind them. In IF modules, they are subjected to analog-to-digital conversion and processed into the original data in the form of images. At the last stage, the data is sent through two centralized boards and a PC adapter to the integrated inter-process communication (IPC) module, where the final analysis of the data takes place. Potentially dangerous objects are automatically detected and calculated, their exact location is displayed. Each panel also contains a synthesis generator for signal initiation, as well as auxiliary elements such as a battery, signal distribution, interface ports, and display elements.

Panel structure R&S QPS

Figure 4. The scanner has a modular design. The external RF interface is distributed in 32 clusters in a checkerboard pattern.

The QPS200 is designed for full scans in as little as 32ms per panel. Computer analysis currently takes a few seconds, and this time will be significantly reduced in the future through the use of more powerful data processing technologies. High-performance graphics processing units (GPUs), optimized by the graphics card industry for massively parallel processing, open up new possibilities on the road to real-time analysis, a prerequisite for future development.

Automatic detection task

At first glance, the body scanner works just like a classic photo booth. The person is illuminated, the reflected light is reproduced on the media (in the case of a scanner, data instead of paper) and an image is developed using the scanner software. However, a fully automatic scanner is not designed to create photographs for human viewing. Instead, its purpose is to provide an interpretation of the image, its evaluation, which is a much more difficult task.

The goal is both simple and complex: to detect all potentially dangerous objects that are carried on the body or in clothing, regardless of the type, size, location and composition of the material. procedures, that is, finding specific objects by pattern matching, will definitely fail. For example, there are too many materials and shapes that can be used as firearms or knives. The scanner had to be able to recognize specific objects based on their characteristics and purpose, regardless of shape, material, and this was a hopeless attempt. Therefore, the task of scanning is not to identify objects, but to identify areas on the body that, when assessed by analysis software, are significantly different from areas that do not arouse suspicion. The task of the developers was to teach the software to determine what is considered not suspicious. However, any attempt to do so on the basis of a "whitelist" of harmless things is also a futile task for the same reason as outlined above. Too many possible variations arise even with a simple example, such as menswear. Whether the person being examined is wearing a pullover or shirt, whether it is made of wool or synthetics, whether it closes with a zipper or buttons, which, in turn, can be large or small, made of plastic, metal or mother-of-pearl, they are located on middle or side, whether a lanky guy is standing in front of the scanner, or a hefty six-and-a-half-foot tall man, the scanner should evaluate all this and more without error and let them go through the examination procedure as usual. It was clear that a completely new approach would be required to solve this problem, which would combine the methodologies of image processing, machine learning and, very importantly, deep learning, a modern method of creating artificial intelligence.

Each scan creates a huge amplitude and phase dataset from the 3D scan volume that can be used as a basis for analysis. The scanner works similarly to a vector network analyzer. The received signals are compared with the transmitted signals in amplitude and phase, and the differential value contains all the necessary information about the test object. The challenge is to interpret this information through proper modeling, that is, by mapping the physical data into specific characteristics and attributes of the object. Examples of these attributes include signal intensity, surface roughness, and multiple reflection strength. In fact, over a thousand different attributes can be defined and combined into a high-dimensional attribute space. Suspicious objects or materials leave behind characteristic identification data in the place where they appear in certain subsets of attributes (=combinations of attributes) in certain ways. Classifiers are used to model these subsets (Figure 5).

Comparison of measured data with object characteristics using classifiers

Figure 5. Attributes are extracted from the basic physical information (radii and phases) and they are combined into n-dimensional classifiers, each of which responds to a specific characteristic or class object. In this example, there are three classifiers, each with two attributes. Combining all classifiers gives the final result of the discovery.

Figure 6 demonstrates this principle based on a classifier that uses attribute signal intensity and surface roughness. In this two-dimensional attribute space, an unsafe area of the body can be distinguished from an area in which, for example, a black powdered substitute was hidden under clothing. When deciding what exactly to highlight as a suspicious object, clear boundaries are an important criterion for the convenience of using the classifier.

Classifier principle

Figure 6. An example of a classifier with two attributes to determine the characteristics of a particular object. Attributes should be chosen so that a clear decision boundary can be defined; Two possible boundaries are shown here.

At the time the development of the QPS100 was started, it was still necessary to manually define and parameterize suitable attributes and classifiers (feature engineering). However, over the past few years, there have been huge advances in the field of machine learning, in particular deep learning. The latest version of the detection software has also been trained using deep learning algorithms.

Deep learning has replaced traditional machine learning algorithms in many applications. Google Android voice recognition, Facebook face recognition and Skype voice translation are based on deep learning. In early 2016, Google's AlphaGo computer program caught everyone's attention by beating numerous world-class Go players in a feat previously thought impossible. The game power of the software lay in the algorithms and analysis rules generated by neural networks using deep learning.

You can achieve amazing results with neural networks when it comes to pattern recognition. For example, networks especially suited for image processing, called convolutional neural networks, are now outperforming even humans at tasks like traffic sign recognition. In order for a neural network to complete a task, its topology and neuron switching functions must be perfectly tuned. Therefore, it took a lot of effort to develop the networks that underlie the R&S QPS software, and it also entailed huge costs. To find out if the network will work as intended, it must first be sufficiently prepared using data that meets high quality requirements**. In this case, the software was provided with a large set of labeled training data obtained by scanning many thousands of test subjects***. Labels are used to indicate any problem areas, if any, on the test object. The type of problem (knife, explosives, etc.) doesn't matter. From the vast number of samples processed, the software learns on its own what the alarming samples look like. In an extremely intensive processor optimization process that changes millions of parameters, the deep learning algorithm works through the database, finding those attributes and classifiers that are best suited to identify cases of violations. The solution to the problem obtained in this way is implemented in the scanner firmware. The overall learning and application cycle is highly unbalanced in terms of the time required. The extended learning phase (long calculations are performed on the GPU cluster) creates a program that, in actual use, can make decisions in seconds.

Deep learning provides decisive advantages in scanner software development. This method not only achieves high detection quality, but is also particularly attractive because the results are generated automatically. Software becomes a partner in development, freeing engineers from monotonous routine tasks. Instead, engineers can invest their time in improving neural networks and deep learning algorithms, leading to even better detection results.

Executive Summary and Future Developments

With the QPS security scanner series, Rohde & Schwarz is opening a new chapter both for this category of devices and for aviation safety. Innovative hardware and software solutions meet the requirements of airport security workers while meeting the expectations of passengers to the maximum. Operators can integrate compact devices into a barrier-free checkpoint to ensure high passenger throughput.