Fiber Optic Interference Sensor
The fibre-optic interferometric sensor is a system enabling the detection and localisation of physical mechanical disturbances affecting the sensory part of the system. The sensor system is built on the basis of two Mach-Zehnder interferometers, utilising the same optical fibres but with opposite directions of light propagation. The construction of the interferometric sensor system requires the use of 3 single-mode optical fibres.
In the system's construction, two fibre-optic sections can be distinguished. The section sensitive to external disturbances comprises the optical fibres that are the arms of the interferometer, as well as the transmit-receive fibres respectively transmitting the output signals from the interferometers and ensuring the transmission of optical power to the interferometers.
Based on the analysis of interference contrast and through appropriate signal processing, it is possible to generate an alarm signal and locate the site of the external disturbance. Additionally, thanks to the application of appropriate modulation of the power radiation, the system automatically adapts to environmental changes affecting the sensitive part of the system, ensuring automatic compensation of slow-varying background signals.
The interferometric sensor system is capable of monitoring multi-kilometre zones (up to 49 km) along with the localisation of the disturbance site with an accuracy of 0.05% of the total fibre length, thereby providing the possibility of dividing the protected zone into several dozen-metre security zones with the ability to freely configure the location of detection zones.
Monitoring of the integrity of multi-kilometre fibre-optic transmission lines.
Generation of an alarm signal and localisation of the site of the external disturbance.
High security of data transmitted in the supervised transmission channel.
Simplicity of installation and fault removal.
Perimeter protection of extensive facilities.
Protection of pipelines.
Protection of borders.
calculation of cross-correlation and its normalisation,
determination of the disturbance location from the correlation,
checking whether the location is within the specified range,
checking whether the correlation level exceeds the specified value,
checking the shape of the correlation waveform at the disturbance location.
The interferometric sensor is characterised by simplicity of installation and fault removal resulting from damage to the transmission path (thanks to the possibility of using standard telecommunication optical fibres). After a failure occurs on the line, it is possible to quickly restore the system's functionality.
The interferometric sensor can be used as a module for monitoring the integrity of telecommunication lines, and thanks to the possibility of using sensitive fibres for data transmission, it ensures high security of data transmitted in the supervised transmission channel. A security system based on the interferometric sensor can be equipped with maps on which alarm locations are visualised.
The system additionally offers a software operator interface module, through which visualisation of the system's operation and configuration of system operating parameters are possible.
The system was developed as a research and development project, within the framework of the IOE WAT and KenBIT Sp. z o. o. Consortium.