The primary difference between a metal detector and a full body scanner lies in the types of materials they are capable of detecting.
Core Detection Capabilities
Metal detectors are designed specifically to identify the presence of metal objects. They work by using electromagnetic fields that react when metal passes through them, triggering an alarm.
In contrast, full-body scanners are advanced security imaging systems that can detect a wider range of materials, including both metal and non-metal objects. This capability became particularly important for security screening, especially after various airliner bombing attempts in the 2000s, where non-metallic explosives or weapons posed an increasing concern. By using technologies like millimeter waves or backscatter X-rays, these scanners create an image that can reveal items hidden under clothing, regardless of whether they are made of metal or not.
Advanced Screening Features
Beyond detecting objects hidden under clothing, some modern full-body scanners possess even more sophisticated detection abilities. According to security information, some scanners can also detect swallowed items or items hidden in the body cavities of a person. This provides a more comprehensive screening process compared to traditional metal detection alone.
How They Work (Simplified)
- Metal Detectors: Utilize electromagnetic technology. They emit an electromagnetic field and detect changes in the field when a metal object is present.
- Full Body Scanners: Employ various imaging technologies such as:
- Millimeter Wave Scanners: Use non-ionizing radio frequency energy to create a 3D image.
- Backscatter X-ray Scanners: Use low-level X-rays that bounce off the skin to create a 2D image.
These different technologies allow full-body scanners to "see" through clothing and identify objects that wouldn't trigger a metal detector.
Applications
Both technologies are crucial for security but are often used in different contexts or as part of a multi-layered security system:
- Metal Detectors: Commonly used in places like:
- Courthouses
- Schools
- Event venues
- Entrances to buildings
- Part of airport security, often before or after body scanners.
- Full Body Scanners: Primarily used in high-security environments requiring detection of non-metallic threats, such as:
- Airports (often mandatory for passengers)
- Prisons
- Some government buildings
Key Differences at a Glance
Here is a table summarizing the main distinctions:
| Feature | Metal Detector | Full Body Scanner |
|---|---|---|
| Primary Detection | Metal objects only | Metal, non-metal, and other materials |
| Technology | Electromagnetic fields | Millimeter wave, Backscatter X-ray, etc. |
| Detection Location | On or immediately beneath clothing | On, beneath clothing, in body cavities (some models) |
| Image Output | Audio alert/light when metal is found | Detailed image revealing hidden objects |
| Threat Types | Metallic weapons | Metallic weapons, explosives, contraband, etc. |
Understanding the capabilities of each technology helps explain why security checkpoints utilize different screening methods to ensure comprehensive safety.
