mmWave security inspection has become a reality, adding another possibility for human safety protection

At six in the morning, at the security checkpoint of Beijing Daxing Airport, sleepy business travelers were already ready to go. It was a little different from every previous trip. This time they were not assigned to the same-sex hand inspectors like lambs, but were prompted to stand in an instrument like a shower room.
 

On the computer screen next to it, all the passenger's belongings were displayed in 360 degrees.

This is not some high-tech exercise.

Millimeter wave security scanning equipment is increasingly appearing in the bidding documents of many customs, airports and even the Winter Olympics Organizing Committee. In other words, in the future, everyone may have to undergo millimeter wave inspections before watching a game, taking a train, attending a meeting, or even simply commuting to get off work.

The impact of the introduction of new technologies on public safety is closely related to everyone and is also an important silhouette in the wave of domestic technology development.

A brief history of security inspection:

Every technical advancement is mixed with blood and tears

Unlike many preventive technologies, every advancement in security inspection models is accompanied by tragedy and bloodshed.

Looking back at every technological iteration in the history of human development, it was all driven by a series of security incidents.

The earliest security gate for prohibited items, the "Magnet Gate" of the Afang Palace, was specially added when the Qin Shihuang Emperor rebuilt the palace in 212 BC after the assassination of Qin Shi Huang by Jing Ke. This North Gate was made of "magnetic stones" and was reserved for foreigners, who could search people by the reaction between magnets and iron weapons.

Of course, the "manual inspection" familiar to modern people is also indispensable. At this time, it is not technology that is relied on, but simple and crude, but effective. Daily operations such as entering the city are omitted. In the imperial examination, if the scholars accidentally smuggle private goods into the city, the examiners and candidates of the current period will be executed or exiled. Therefore, before the exam, a "meticulous to the chrysanthemum" security check is indispensable. If modern people travel back to ancient times and want to take the "college entrance examination", they must first weigh their own small bodies. In the warm and cold March, they are stripped down to only a deep coat, barefoot and holding shoes, and being touched thoroughly by the security guards. Can they bear this punishment...

Electromagnetic Era

Similar to the "magnetic door", metal detection technology has actually existed for a long time before it was introduced into the common "security door" in modern times. It was just mostly used in industry and mining to check the purity of minerals, or placed on looms to prevent broken needles from being caught in the fabric and damaging the machine.

It was not until the 1970s, after a series of civil aviation hijacking incidents, that China truly entered the field of security inspection.

In 1969 alone, there were 82 hijackings around the world. The United States was the most affected, and it began to set up air marshals in 1970. However, real risk prevention must start on the ground, so in 1972, the Federal Aviation Administration (FAA) required all airlines to begin security checks on passengers and luggage.

It is never too late to mend the fence after the sheep have been lost. Thus, the "big sheepfold" model officially entered the historical stage, and also started a series of iterations of modern security inspection technology.

The so-called "big sheepfold" mode means that all luggage is checked at the first security check line, and after completing the check-in and other formalities, the second security check line (that is, the airport security area) completes the hand luggage and personal inspection. This departure security area is also called the "sheepfold".

Today, this kind of setup can still be seen in many public places such as airports and high-speed rail stations. Passengers line up like lambs, waiting for a series of tests such as security gates, handheld detectors, and body searches.

During this stage, electromagnetic induction, or metal detection technology, was the dominant technology.

The security door detects the body through infrared radiation sensors. When it detects metal objects on the body, the corresponding area alarm lights will flash and an alarm will sound.

The principle of handheld metal detectors is basically similar. Anyone who has experienced subway security checks during the morning rush hour must have questions about this technology. It sends random alarms, is inefficient, and cannot identify non-metallic and other dangerous goods. Is this type of security check really useful?

Although it has its limitations, it is the best general solution for security systems in public places.

X-ray Era

Security inspection has truly reached a new level since the introduction of X-ray technology.

It uses X-rays to penetrate objects, transmits the signals obtained by penetrating the objects to the processor for signal processing, and finally transmits the signals to the controller to display the signals on the display. The security inspector determines whether the objects are prohibited items based on the displayed images.

Does it look familiar? Yes, this is the counter security check that you can see in airports, subways, high-speed railways and other places today.

Initially, X-ray security inspection machines were mainly used abroad. It was not until the "Zhuo Changren hijacking incident" in 1983 and several hijackings in mainland China in the 1990s that China's civil aviation began a comprehensive "process transformation" and all checked baggage was inspected.

Of course, criminals are also becoming more capable of causing trouble. For example, the Lockerbie air crash in 1988 directly blew up an airplane, which required the security inspection system to be able to detect explosives. In 2006, someone planned to blow up ten airplanes in the UK with liquid bombs, and the 9/11 incident, all of which put forward higher requirements for the continuous detection and resolution capabilities of security inspection equipment.

Therefore, more advanced X-ray CT scanners came into use. Compared with baggage X-ray security scanners, they have a higher detection rate for dangerous goods.

It can not only provide high-definition color 2D images, CT slice images and 3D images of luggage passing through the aircraft, but also use information such as the density and effective atomic number of the items passing through the aircraft to realize automatic early warning recognition and image inspection of various prohibited items. It has now become a standard feature of major airports in various countries.

Millimeter wave era

The security system has been well-defended, but the devil is always stronger than the saint, and criminals are not easy to deal with. During Christmas in 2009, a Nigerian man managed to sneak onto a plane by hiding a high-powered bomb in his crotch, and nearly blew up Northwest Airlines Flight 253.

Although the crisis was discovered and resolved in time, how to prevent people from hiding items on their bodies to cause trouble without causing harm to the human body has become a new problem for public security checks.

As a result, millimeter wave human imaging systems began to be used in aviation fields around the world.

Millimeter waves can detect not only metals, but also non-metals, explosives, etc. They can also image the penetration of ordinary clothing to determine whether there are any suspicious items hidden on the surface of the body being inspected. Compared with X-ray security scanners, the transmission power of millimeter waves is less than one thousandth of the electromagnetic radiation of mobile phones, making them more easily accepted by the public in personal inspections.

(The left picture shows the image of an X-ray security scanner, and the right picture shows the image of a millimeter wave security scanner)

The global security inspection industry in a changing situation

Looking back at the evolution of security inspection technology, we will find that some things we are used to are being changed:

First, the technology is becoming more forward-looking. Equipment upgrades are no longer just passive defense and upgrades after a specific security incident occurs, but are more forward-looking. For example, before the crotch bomb incident in 2009, Amsterdam Schiphol Airport in the Netherlands had already installed the world's first millimeter wave equipment in 2007.

In the future, "the devil is one foot high and the road is ten feet high". Taking the initiative to prevent security risks will further accelerate the cyclical iteration of security inspection equipment.

In addition, the addition of AI and the Internet of Things has enabled intelligent security inspection to be used as an overall solution, breaking the state of "information islands" in each link. Especially after combining with digital networks such as smart cities, the concept of "big security inspection", that is, joint inspection, has begun to emerge, integrating the design of the entire chain of services such as security inspection, customs, inspection and quarantine, public security, and urban rail, plus the support of AI algorithms such as automatic identification of dangerous objects, face recognition, and intelligent management of system interfaces, which has subtly improved the overall efficiency of security inspection.

Under this trend, China's scientific and technological forces are no longer content to be just "primary school students" and be dominated by European and American experience as in the past, but have begun to actively iterate and export their own solutions.

For example, in millimeter wave equipment, the situation of foreign manufacturers dominating X-ray security equipment in the last century has been changed. At the same time, relevant access standards have been followed up to guide the independent research and development growth of the domestic market. In the layered system solution, Shanghai Hongqiao and Beijing Daxing Airports have also become benchmarks for advanced technology support.

Under the new circumstances, what standards need to be re-established for physical security checks?

From accident-driven, policy-led, overseas-dominated, single-point upgrades to today's localization, digitization, and networking, security inspection technology is reorganizing itself around the safety dimension of people.

The evolution from X-ray security inspection machines, which have been used for more than 20 years, to millimeter wave equipment also contains great business opportunities. Of course, the traditional industrial upgrading ideas are also constantly being forged by the development of smart cities.

In the process of upgrading millimeter wave equipment, several key points may be the most concerned:

1. Security. The first secret of security inspection system design is security, which means that there must be highly reliable software and hardware engineering support. Not only must the technology be independent and controllable, but also targeted recognition algorithm training must be carried out for China's own contraband library. Domestic millimeter wave equipment will usher in an explosive period.

2. Cost-effectiveness. The popularization of each generation of security inspection technology is inseparable from the trade-off and game between performance and price. Domestic equipment undoubtedly has an advantage in cost, but millimeter wave technology also relies on a series of intellectual property support such as integrated circuit layout, sensor components, deep learning algorithms, and imaging technology. How Chinese security inspection equipment manufacturers can successfully overcome these difficulties requires market incubation and policy guidance.

3. Scalability. As mentioned earlier, security inspection is moving from passive defense to active prediction, which requires the designers of security inspection systems to fully research and predict the future international situation, industry evolution, technological development, and industry demand trends, so as to leave flexible expansion interfaces for technology updates during system development to reduce the hidden costs of rapid updates.

Violent attacks have been a topic of great pain to the whole society since ancient times. Every advancement in security inspection technology is pushing the safety standards of people forward one step further.