Solid-Phase Reference Baths for Fiber-Optic Distributed Sensing.

Area of Science:

• Geosciences
• Industrial Sensing
• Optical Fiber Technology

Background:

• Raman backscatter-based Fiber-Optic Distributed Sensing (FODS) requires stable temperature references for accurate measurements.
• Traditional liquid-phase water baths present limitations in stability and precision for FODS calibration.
• Accurate temperature sensing is crucial for translating photon intensities to meaningful data in geosciences and industry.

Purpose of the Study:

• To design and evaluate a novel Solid-Phase Bath (SoPhaB) for precise temperature calibration in FODS.
• To provide a high-accuracy and high-precision alternative to traditional water baths for FODS applications.
• To demonstrate the SoPhaB's suitability for diverse environmental conditions and industrial uses.

Main Methods:

• Development of a Solid-Phase Bath (SoPhaB) utilizing ultrafine copper and thermoelectric elements (Peltier).
• Integration of two built-in platinum wire thermometers for precise temperature monitoring.
• Laboratory and field testing in extreme environments (Arctic polar night, peak summer) to assess performance.

Main Results:

• The SoPhaB precisely controls copper body temperature within ±0.04 K.
• Spatial temperature differences across the SoPhaB are less than 0.05 K, even with large external temperature variations (ΔT > 40 K).
• The SoPhaB enables reduced calibration bias and spatiotemporal uncertainty using shorter fiber-optic sensor sections (<5 bins).

Conclusions:

• The Solid-Phase Bath (SoPhaB) is a highly accurate and precise calibration tool for Fiber-Optic Distributed Sensing (FODS).
• Its robust design and mobile capability make it suitable for demanding geosciences and industrial applications.
• The SoPhaB overcomes limitations of traditional water baths, enhancing the reliability of distributed temperature sensing.