Review of high temperature measurement technology based on sapphire optical fiber

Wang, Botao; Niu, Yanxiong; Xudong, Qin; Yin, Yiheng; Ding, M. D.

doi:10.1016/j.measurement.2021.109868

Cited by 47 publications

(23 citation statements)

References 76 publications

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“…The calibration function

is calculated as a 4th order polynomial, where the fit was weighted by the temperature uncertainties. The resulting sensitivity is between 26 pm/K at 500 °C and 39 pm/K at 1600 °C, which is comparable to other published data [ 11 , 14 , 17 , 18 , 26 ].…”

Section: Characterization and Calibration Of The Hybrid Sensorsupporting

confidence: 90%

“…The transmission of more than 30,000 modes has important consequences for the interpretation of the reflected Bragg signal. The distinct peak, known from single-mode FBGs, becomes a rather wide and asymmetric shape [ 17 ]. This can be understood by considering the Bragg condition for the wavelength

for a periodic perturbation in the fiber [ 24 ]:

…”

Section: Theorymentioning

confidence: 99%

“…Sapphire fibers are a promising alternative as they remain optically and mechanically stable at very high temperatures. It is possible, albeit challenging, to inscribe FBGs in sapphire fibers [ 14 , 15 , 16 , 17 ]. Habisreuther et al [ 11 ] previously reported using a sapphire FBG (S-FBG) sensor up to 1500 °C in an induction furnace.…”

Section: Introductionmentioning

confidence: 99%

“…Habisreuther et al [ 11 ] previously reported using a sapphire FBG (S-FBG) sensor up to 1500 °C in an induction furnace. The sensor offered a temperature resolution of

K at a monitoring rate of 20 Hz [ 11 ], but a quantification of the measurement uncertainty is still missing, as can be seen in [ 11 , 17 ]. The FBG was found to even withstand exposure to 1900 °C [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

“…The combined effect smears the reflection peak in an asymmetric manner, with the consequence that data processing is more challenging [ 17 ]. However, since the shape of the irregular peaks results from the optical and geometrical properties of the fiber, this pattern is stable and can be used for sensing applications.…”

Section: Introductionmentioning

confidence: 99%

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Metrological Characterization of a High-Temperature Hybrid Sensor Using Thermal Radiation and Calibrated Sapphire Fiber Bragg Grating for Process Monitoring in Harsh Environments

Eisermann

Krenek

Habisreuther

et al. 2022

Sensors

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Fiber Bragg gratings inscribed in single crystalline multimode sapphire fibers (S-FBG) are suitable for monitoring applications in harsh environments up to 1900 ∘C. Despite many approaches to optimize the S-FBG sensor, a metrological investigation of the achievable temperature uncertainties is still missing. In this paper, we developed a hybrid optical temperature sensor using S-FBG and thermal radiation signals. In addition, the sensor also includes a thermocouple for reference and process control during a field test. We analyzed the influence of the thermal gradient and hotspot position along the sensor for all three detection methods using an industrial draw tower and fixed point cells. Moreover, the signal processing of the reflected S-FBG spectrum was investigated and enhanced to determine the reachable measurement repeatability and uncertainty. For that purpose, we developed an analytical expression for the long-wavelength edge of the peak. Our findings show a higher stability against mechanical-caused mode variations for this method to measure the wavelength shift compared to established methods. Additionally, our approach offers a high robustness against aging effects caused by high-temperature processes (above 1700 ∘C) or harsh environments. Using temperature-fixed points, directly traceable to the International System of Units, we calibrated the S-FBG and thermocouple of the hybrid sensor, including the corresponding uncertainty budgets. Within the scope of an over 3-weeks-long field trial, 25 production cycles of an industrial silicon manufacturing process with temperatures up to 1600 ∘C were monitored with over 100,000 single measurements. The absolute calibrated thermocouple (Uk=2≈1K…4K) and S-FBG (Uk=2≈10K…14K) measurements agreed within their combined uncertainty. We also discuss possible strategies to significantly reduce the uncertainty of the S-FBG calibration. A follow-up measurement of the sensor after the long-term operation at high temperatures and the transport of the measuring system together with the sensor resulted in a change of less than 0.5 K. Thus, both the presented hybrid sensor and the measuring principle are very robust for applications in harsh environments.

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“…The calibration function

Section: Characterization and Calibration Of The Hybrid Sensorsupporting

confidence: 90%

for a periodic perturbation in the fiber [ 24 ]:

…”

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Habisreuther et al [ 11 ] previously reported using a sapphire FBG (S-FBG) sensor up to 1500 °C in an induction furnace. The sensor offered a temperature resolution of

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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