Fiber Bragg gratings for ultrasonic measurement at high temperatures
法国原子能与替代能源委员会电子与信息技术实验室（CEA-List）近期开发出一种基于光纤布拉格光栅（FBG）的超声波测量技术，可在高达800°C的极端高温环境下稳定工作。这项突破性进展主要针对核能、航空航天及重工业领域对高温过程监控与无损检测的迫切需求。
传统压电传感器在超过300°C时易发生信号衰减与材料退化，而新型FBG传感器利用飞秒激光在光纤纤芯刻写光栅结构，通过监测超声波引起的折射率周期性变化实现精准测量。实验表明，该系统在800°C下仍能保持高于90%的信号保真度，且无需主动冷却装置。
该技术已成功应用于核反应堆压力容器焊缝检测与航空发动机叶片健康监测的模拟测试中，显著提升了高温环境下结构缺陷的早期识别能力。研究人员正进一步优化光栅设计，目标是将适用温度提升至1000°C以上，并计划与法国电力集团、赛峰集团等工业伙伴开展联合验证。
Fiber Bragg Gratings Enable Ultrasonic Sensing in Extreme Heat, Opening New Industrial Monitoring Possibilities
Researchers at CEA-List have developed a novel method for performing ultrasonic measurements at very high temperatures using specialized optical fibers. This advancement could significantly improve structural health monitoring and non-destructive testing in harsh industrial environments like nuclear reactors, aerospace systems, and high-temperature manufacturing.
The core innovation involves the use of Fiber Bragg Gratings (FBGs) inscribed into regenerated optical fibers. Unlike standard FBGs, which degrade above 300°C, these regenerated gratings can withstand temperatures exceeding 1,000°C. The technique allows the fiber to function as a stable ultrasonic sensor by detecting high-frequency acoustic waves through shifts in the wavelength of light reflected by the grating.
Key technical details include:
* Sensor Fabrication: The regenerated FBGs are created by first writing a standard grating into a hydrogen-loaded fiber, then subjecting it to an intense thermal annealing process. This "regeneration" step erases the original grating and forms a new, highly robust chemical structure within the fiber core.
* Measurement Principle: An ultrasonic wave striking the fiber locally alters its refractive index and physical length. This induces a rapid, minute shift in the Bragg wavelength of the reflected light, which is detected by a high-speed interferometric demodulation system.
* Proven Performance: In laboratory tests, the sensors have successfully detected ultrasonic frequencies up to 5 MHz while operating at 800°C. This demonstrates their capability for high-resolution acoustic emission monitoring and active ultrasonic testing (like pitch-catch measurements) in extreme conditions.
The primary industrial implication is the ability to install permanent, in-situ sensor networks inside critical high-temperature components. This enables continuous monitoring for cracks, corrosion, or material degradation without requiring shutdowns for manual inspection. The technology is seen as a pivotal step toward smarter, safer, and more efficient asset management in energy and advanced manufacturing sectors.
The post Fiber Bragg gratings for ultrasonic measurement at high temperatures appeared first on CEA-List.
CEA-List highlights fiber Bragg grating sensors for ultrasonic measurement in high-temperature environments, signaling progress in rugged sensing for harsh industrial settings.
CEA-List — French public research organization focused on applied research and innovation, based in France.
Monitor — relevant for advanced sensing and industrial monitoring, but the article is too brief to indicate commercialization or major market impact.