These systems use light signals to measure temperature, strain, and acoustic events along a fibre-optic (FO) cable near or attached to a pipeline. DNV is a leader in verifying distributed fibre-optic sensing (DFOS) systems for pipeline leak detection. Unlike traditional electrical temperature measurement (thermocouples & RTD), the length of the fiber optic cable is the temperature. Sensing systems based on Brillouin and Raman scattering are used, for example, to detect pipeline leak-ages, to verify pipeline operational parameters and to prevent failure of pipelines in-stalled in landslide areas, to optimize oil production from wells, and to detect hot spots in high-power.