Fibre Optic Temperature Sensor Using Controlled Thermal Perturbation

The patent applies preliminary action by introducing a known thermal variation (temperature perturbation) to the fibre optic cable before measuring the response. A controllable thermal element heats the cable in a predetermined manner, and the Rayleigh backscatter response to this known input is analyzed to determine absolute temperature. This preliminary thermal stimulus enables the system to extract absolute temperature information that would otherwise be unavailable from change-only measurements.

The patent implements feedback by using the detected Rayleigh backscatter signal to determine the absolute temperature, which then feeds back into the system for continuous monitoring and control. The measured temperature information is used to maintain accurate temperature profiles along the fibre optic cable, enabling closed-loop temperature management and continuous absolute temperature determination.

The patent substitutes the Brillouin/Raman scattering mechanism with Rayleigh scattering-based thermal response analysis. Instead of relying on the frequency shift or intensity ratios inherent to Brillouin and Raman scattering, the system uses Rayleigh backscatter in response to a controlled thermal perturbation. This substitution maintains the ability to measure absolute temperature while achieving faster response times characteristic of Rayleigh-based sensing.

The patent changes the measurement parameter from relying on intrinsic scattering properties (Brillouin frequency shift, Raman intensity ratios) to measuring the dynamic thermal response of the fibre to a controlled temperature perturbation. By monitoring how the Rayleigh backscatter signal responds to the applied thermal variation, the system determines absolute temperature with faster response compared to conventional DTS methods.

The patent applies universality by designing the controllable thermal element to serve multiple functions: it acts as both a heating element for introducing thermal variations and as part of the sensing system itself. The same thermal element that perturbs the fibre for measurement purposes also serves as a reference for the thermal response analysis, eliminating the need for separate reference sensors and reducing overall system complexity.

The patent implements self-service by using the fibre optic cable itself as the medium for both sensing and thermal actuation. The controllable thermal element integrated into the cable structure allows the system to self-generate the thermal variations needed for measurement, and the fibre's own thermal response characteristics are used to determine absolute temperature, reducing dependence on external complex measurement systems.