A brilliant idea
With endless
Possibilities
The principle of Sensor Line’s fiber optic sensors is as simple as ingenious: under load, the optical transmittance decreases. These changes are detected by an opto-electronic interface and then transformed into signals for traffic data processing.
Benefits
- Cheapest permanent sensor installation on the market
- No mechanical parts
- Adapts to pavement contour
- Optimized embedding materials from Sensor Line
- Light-weight and compact sensor implementation
- Minimum sensitivity to lateral pressure
- Ultra-fast, true DC response
- Outstanding trigger accuracy
Microbending
An optical fibre consists of a glass core surrounded by a cladding with a lower refractive index. Light travelling through the core cannot penetrate the cladding but is instead reflected without any loss. However, in order to transmit light over long distances in this way, the fibre must have a uniform shape, run straight and have a very consistent refractive index. If the fibre is subjected to stress at any point, this not only causes microscopic deviations along the fibre axis but also leads to changes in the refractive index, thereby significantly compromising both requirements. The light can then escape from the fibre core. This loss can be measured as a reduction in the optical power arriving at the fibre end. This is the principle utilised in Sensor Line’s fibre-optic sensors. Unlike other fibre-optic measurement principles, this requires neither a specially treated fibre nor any additional optical components.
A constant quantity of light is being guided along an optical fiber. At moderate curvatures light loss is hardly noticeable. Below a certain bend radius light loss grows dramatically. Light exits due to “microbending”. The quantity of remaining light varies according to the magnitude of the “microbending” effect and can be easily measured with a simple detector.
