Short Answer 
Airport scanners, including X-ray and 3D models, are primarily designed to detect security threats such as explosives and weapons, while also capable of identifying various items including currency. They use advanced imaging technologies, but their main purpose is not to count currency but to ensure travel safety.
Step 1: Understanding Airport Scanners
Airport scanners, including both X-ray and three-dimensional scanners, are designed to inspect luggage thoroughly. They utilize advanced imaging technologies to reveal the contents of bags and items passengers carry. Most importantly, these scanners are primarily aimed at identifying security threats like explosives and weapons.
Step 2: Detection Capabilities
In addition to detecting weapons, these scanners can recognize a variety of objects, including currency notes. The scanning devices may employ different technologies such as:
- Gamma ray scanning
- X-ray scanning
- Neutron scanning
This makes them effective in revealing various items inside luggage, not just security threats.
Step 3: Currency Features and Scanner Functionality
Modern currency often has unique security features that interact with light. For instance, U.S. currency utilizes thin film interference effects, while countries like Australia use diffraction gratings in polymer dollars. While scanners can pick up these features, it’s crucial to understand that their main mission is not to count currency, but rather to ensure the overall safety and security of air travel.