In addition to passenger luggage, most aircraft also carry a significant amount of cargo. All these goods must be inspected before loading.
Most airports employ one of three systems to do this:
Medium X-Ray Systems – These are stationary systems that scan for suspicious items.
Mobile X-ray System – A large truck carries the complete X-ray scanning system. The truck was driving slowly alongside another truck, stopping to scan the truck’s entire location for suspicious items.
Fixed Site System – This is a whole building, basically one giant x-ray scanner. A tractor-trailer is pulled into the building, and the entire truck is scanned in one go.
X-ray baggage scanner
Checking your luggage: CT scanners
The first security check your checked baggage goes through depends on the airport. In the United States, most major airports have computed tomography (CT) scanners. A CT scanner is a hollow tube that goes around your bag. The X-ray mechanism slowly revolves around it, bombarding it with X-rays and recording the resulting data. A CT scanner uses all this data to create very detailed tomograms (slices) of the bag. From this tomography, the scanner is able to calculate the mass and density of individual objects in the pack. If the mass/density of the object falls within the range of hazardous materials, the CT scanner alerts the operator to the presence of a potentially hazardous object.
Please go through: Metal Detector
All public access to the airport is through the terminal building, everyone has to go through a metal detector and everything has to go through an x-ray machine.
Almost all airport metal detectors are based on pulse induction (PI). A typical PI system uses a coil on one side of the arch as the transmitter and receiver. The technology sends powerful short pulses of electrical current through a coil. Each pulse produces a brief magnetic field. When the pulse ends, the magnetic field reverses polarity and collapses suddenly, creating a sharp electrical spike. This spike lasts for a few microseconds (millionths of a second) and causes another current to flow through the coil. The subsequent current, called a reflected pulse, lasts only about 30 microseconds. Then send another pulse and repeat the process. A typical PI-based metal detector sends about 100 pulses per second, but depending on the manufacturer and model, the number can vary widely, from about 25 pulses per second to over 1,000 pulses per second.
Slotted Metal Detector
Step by Step Through: X-Ray Systems
When you go through the metal detector, your belongings will also go through the X-ray system. A conveyor belt sends each item through the X-ray machine. X-rays are electromagnetic waves like light, but with higher energy, so they can penetrate many materials. The machines used at airports are usually based on dual-energy X-ray systems. The system has an X-ray source that emits X-rays, typically in the 140 to 160 kilovolt peak (KVP) range. KVP refers to the penetration of X-rays. The higher the KVP, the farther the x-rays penetrate.