How does walk through metal detector work?
The issue of security has become a paramount concern in today’s world. Given the range of threats that are faced by society in these times, it is only a given that a range of security measures have been taken up by society, in one form or another.
Of the many such measures that have been taken, one of them most iconic would be that of metal detectors. They are the security devices that have become an important feature wherever there is a possibility of a security threat. You can find these today in places such as important public buildings, airports, seaports, railway stations, private establishments and even schools. And indeed, as time passes by, people have started to deploy them in a wide range of places, where they are deemed to be useful.
A GENERAL INTRODUCTION TO METAL DETECTORS
The usage of a metal detector, as the name would suggest, is for the purpose of ‘detecting’ any kind of metal object that a person might be carrying.
The technology has been around for quite some time, and has been used largely for security and safety purposes. Since knives and guns were traditionally made from metal such as steel, these devices were seen as a very effective way to find them, should an unauthorized person be carrying them, on say, a flight or into a secure building.
The military used them for a similar purpose; the detection of landmines. For those who are not familiar with landmines, they are small explosives buried in the ground, which explode on pressure; whether from people or vehicles. Metal detectors help in the detection of these landmines, enabling the safety of both people as well as equipment.
Additionally, hobbyists and historians found another use for it; the detection of buried treasure and antiques. Every once in a while, people have been able to find buried treasure of one sort or another in places around the world. This treasure ranged from pieces of shipwreck to bullet fragments in a historical battlefield, and even full blown treasures on abandoned beaches.
Simply put, this technology has proven itself to be immensely useful to people from all walks of life.
WALK THROUGH METAL DETECTOR
For a very long time, most of the metal detectors in use were restricted to hand-held devices. This made it very difficult for large numbers of people to be properly checked, especially in areas that had a lot of foot traffic; examples of this included airport or public buildings. There were instances where some of the safety checks failed, due to the way in which hand-held technology allowed for the occasional human error.
It was largely for this reason that walk through metal detectors were created. In simple words, it was the same technology, used on a large scale. Walk through metal detectors allowed for the error-prone hand-held devices to be phased out in favor of more reliable technology.
Walk through metal detectors allowed for easier and more reliable means of metal detecting on individuals than ever before. All that a person had to do was walk through the device, which would check whether any pieces of metal existed on him, whether it was a coin, a knife or anything else. If anything was detected, it would set off an alarm and warn the authorities of something awry going on with that individual or group of individuals.
THE FUNCTIONS OF WALK THROUGH METAL DETECTOR
Coming to the subject of how a walk through metal detector works, it is first necessary to understand the nature of a normal metal detector.
A metal-detector works by using the principle of electromagnetism. It is in general known that any kind of electricity would generate a magnetic field around it.
When this electric field passes over a metal object of any kind, such as say a coin or knife, the field passes right through it, the electrons in it are induced to move and produce a magnetic field of their own. This is a phenomenon known scientifically as ‘induction. In addition to this, it also creates a secondary magnetic field as well.
This secondary magnetic field this created is what is detected by the metal detector. Simply put, the first coil induces the magnetic field into the metal object that a person might be carrying, whiles another coil (called a receiver coil) in the same device picks up this potential secondary magnetic field and accordingly sets off an alarm.
All metal detectors work on the same principle, albeit in different ways. A hand-held detector is one of the most common ones even today. But in places where there is a high amount of foot traffic, such as airports, walk through metal detectors are used. Either way, the technology used is more or less the same.
The only difference in the case of a walk through metal detector, in comparison to traditional ones, is the way in which the technology is used. Walk through metal detectors use what is called ‘Pulse Induction’ or PI technology.
The PI system works by sending powerful and short bursts of current through coils of wire. Each of these pulses generates a short magnetic field in the coils of wire.
The magnetic field thus generated, results in the creation of a secondary magnetic field in any potential metal objects that the person might be carrying. Should that be the case, the same is picked up by a receiver coil, which in turn sets off an alarm system.
The entire process takes a very short period of time, ranging in the millionths of a second, with the first pulse burst lasting a few microseconds and the current thus created last for about 30 microseconds.
Walk through metal detectors have these coils placed all around the individual, meaning that metal located in any part of the body can be easily detected by security personnel. In addition to this, modern detectors also allow the personnel to know the exact place where the metal object was detected, making it easier for security checks and inspections to be conducted by authorized personnel.
LIMITATIONS OF THIS TECHNOLOGY
As effective as this technology has proven itself to be, there are indeed a couple of limitations as well.
With the passage of time, the kind of materials available for humanity has increased tremendously. There is no longer a limit to the kind of materials we can use to create the tools we need.
This has become a rather problematic for some of the older metal detectors, which aren’t equipped to detect some of these newer materials. Since they only detect metals and alloys, non-metallic objects can be taken across them without setting off an alarm.
But this concern has already been taken up by the concerned authorities, with measures being steadily brought in. Newer security measures use technology such as X-rays and so on, which allow for even these non-metallic threats to be detected before anything untoward occurs.
In all, it can be summarized that the usage of walk through metal detectors has proved to be of immense help to society.
Because of the way in which they can prevent threats before they occur, they are seen as a highly useful tool for combating potential dangers.
And since they have proven themselves to be useful repeatedly, and the fact that these threats aren’t going to away anytime soon, it can be said with certainty that these devices will be around for a long time to come.