Ultra-Stable Distributed Fiber Optic Sensor for High-Resolution, High-Temperature Monitoring
This invention is a novel optical fiber sensor featuring a custom nanograting structure written into the fiber core using a precision ultrafast laser process. This enhanced design achieves high spatial-resolution, distributed sensing that is stable in extreme, high-temperature (e.g., up to 800 ∘C.) and chemically harsh environments, surpassing the limitations of current monitoring technologies,
Description
The invention is a distributed fiber optic sensor created by using an ultrafast (e.g., femtosecond) laser direct-writing technique to inscribe a nanograting structure directly into the fiber's core. This nanograting consists of a series of spaced, low-refractive-index elements running parallel to the fiber axis, which dramatically enhances the backscattered light signal (Rayleigh scattering) by more than 50 dB. The key innovation is the sensor's exceptional thermal stability, achieved by subjecting the fiber to a high-temperature annealing process. This process stabilizes the nanograting, sometimes by forming nanopores (voids) within the inscribed elements, which prevents the sensor's optical properties from degrading at high operating temperatures (e.g., 800 ∘C.). When coupled with an Optical Frequency Domain Reflectometry (OFDR) system, this sensor allows for highly reliable, high-spatial-resolution (e.g., 1 mm) distributed measurements, such as temperature, in conditions where conventional sensors fail.Applications
- Internal monitoring of reactor assemblies (e.g., Solid Oxide Fuel Cell systems) to map and manage temperature distribution and mitigate thermal degradation.- Distributed temperature and/or chemical composition sensing in energy production systems operating at high heat.
- High-temperature industrial process control where stable sensing in chemically harsh or reactive gas environments is required.
- Applications requiring high spatial resolution sensing (e.g., 1 mm) for detailed thermal profiling, such as R&D or critical component monitoring.
Advantages
- Exceptional High-Temperature Stability: Operational stability is enhanced to allow for reliable measurements at very high temperatures, mitigating thermal degradation.- Enhanced Signal Strength: The nanograting structure enhances the Rayleigh backscattering profile by more than 50 dB, providing a much stronger signal for interrogation.
- High Spatial Resolution: Capable of distributed temperature sensing with fine spatial resolution, such as 1 mm.
- Harsh Environment Suitability: Well-suited for deployment in chemically reactive environments, including fuel gas (e.g., hydrogen) streams within reactor systems.
- Non-Invasive Measurement: Eliminates the numerous electrical wires required by conventional thermocouples, thus preventing measurement errors caused by heat-loss or disruption of gas flow