Microwaves are commonly used for detecting metal in containers at airports because they offer several advantages over other types of radiation, such as X-rays or gamma rays:
Safety: Microwaves are non-ionizing radiation, which means they do not have sufficient energy to ionize atoms or molecules. This makes them safer for human exposure compared to ionizing radiation like X-rays or gamma rays, which can potentially damage living tissues.
Penetration: Microwaves have the ability to penetrate certain materials, including clothing and non-metallic containers, while being reflected by metallic objects. This property allows for the detection of metal hidden within non-metallic objects.
Reflectivity: Metallic objects reflect microwaves very effectively. By emitting microwaves and measuring the reflected signal, metal detectors can identify the presence of metal objects. This reflective property makes microwaves particularly suitable for detecting metallic items.
Lower cost and complexity: Microwaves are relatively inexpensive to produce and operate compared to X-ray or gamma-ray systems. They are also simpler in design and maintenance, which makes them a more practical choice for widespread use in airport security settings.
Reduced health concerns: The use of non-ionizing radiation, such as microwaves, reduces potential health concerns for both passengers and security personnel who are routinely exposed to these scanning systems.
While microwaves have their advantages, it's worth noting that they are primarily used for detecting metallic objects. If a more detailed inspection or imaging of the contents of a container is required, X-ray or gamma-ray scanners may be employed to provide a more comprehensive view. Each type of radiation has its own specific uses and advantages depending on the desired application.