Detection of Tags on Passive Targets

The passive tags consist of a base plate, a reflector, and a specific pattern.

Structure of a Passive Target

1

Base Plate

2

Reflector

3

Specific Pattern

The lighting unit of the sensor emits infrared light, which hits the reflector. The reflector reflects incident electromagnetic waves largely in the direction from which they came, regardless of the direction of incidence and the orientation of the reflector.

The substrate of the reflector consists of small transparent glass spheres, which focus most of the incident light.

Retroreflective Effect

Due to the difference in the refractive index compared to air, the rear surface of the sphere is reflective. Due to this effect, the foil reflects the light back to the sensor. Each tag is defined by its specific pattern.