Introduction to Airport Security Inspection Technology and Principles
1. The technology adopted by the X-ray security inspection machine for baggage items:
The X-ray inspection system measures the number of X photons passing through the object to be detected, and the probability of X being absorbed reflects the density information of the substance to be detected. The transmissive detection method is carried out through the interpretation of the shape and density information of the detected substance by the staff. The X-ray imaging products currently used in airports are basically dual-energy X-ray imaging technology, multi-view X-ray technology, and CT-ray imaging technology.
Compared with a single-energy X-ray inspection system, the use of double-quantity X-rays can obtain the effective atomic number information of the object to be inspected, which improves the system's material resolution capability. CT technology can form three-dimensional images of objects, measure the thickness of substances, and distinguish explosives from other similar substances with low atomic numbers.
2. Check the trace detection technology of explosives:
Ion migration technology will use the "wiping test paper" method to detect traces of explosives on people or carrying packages when the security level is relatively high. The technical principle is: ionize the test sample in the atmosphere or move gas to form ions and then drift in an external electric field. Because the mobility of different samples is different, the different components in the sample are separated in the migration tube. Generally, the heavy molecules go slower than the light ones. In this way, the composition of the sample can be known based on the measured migration time.
Ion mobility spectroscopy technology has now been widely used in drug detection, explosives detection, chemical warfare agent detection, atmospheric and water organic pollution detection, factory toxic gas monitoring, food detection, wood type detection, and other fields.
（As shown in the picture above: Airport security checks usually include security checks for passengers and carry-on luggage, security checks for checked luggage, and security checks at the airport perimeter.）
3. Human imaging technologies currently used in US airports:
Backscatter imaging technology Backscatter technology is a method of analyzing the detected substance based on Compton backscatter. The principle of this type of method is to perform two-dimensional or three-dimensional imaging of an object by measuring Compton scattered X-photons scattered from the detected substance. It can get the distribution information of the electron density inside the tested substance. Backscatter technology is suitable for detecting low-Z organic materials.
4. The human body imaging technology currently used in US airports: millimeter-wave imaging technology Millimeter-wave is generally defined as the frequency band from 30 GHz to 300 GHz, which is between infrared and microwave in the frequency spectrum. Compared with visible light and infrared, this section of the spectrum has a certain degree of penetration for most non-metallic objects, and at the same time has a resolution that microwaves do not have. There are two main millimeter-wave imaging methods: one is passive and the other is active. Passive imaging equipment is a device that uses millimeter waves radiated from the human body to gather imaging. The amount of millimeter-wave rays radiated by objects depends on their physical properties and temperature. The human body radiates more millimeter waves than metals, ceramics, plastic explosives, powdered explosives, clothing, and insulating materials. The millimeter-wave can penetrate any insulating material, all clothing fabrics, and most construction materials.
Currently, most of the active millimeter-wave imaging devices used in the market have higher accuracy than passive ones. In front of the millimeter-wave imaging equipment, the clothes on the human body are missing. Against the silhouette of the human body, the coins, buttons, pens, keys and other objects on the human body are clearly visible. If you hide contrabands such as pistols, bombs, and drugs, you will get a clear view.
Introduction to Airport Security Inspection Technology and Principles (1) - Safeagle