A Highly Sensitive Two-Dimensional Inclinometer Based on Two Etched Chirped-Fiber-Grating Arrays

Area of Science:

• Optoelectronics
• Fiber Optic Sensors
• Instrumentation

Background:

• Accurate inclination measurement is crucial for structural health monitoring and control systems.
• Existing inclinometers often face limitations in sensitivity, resolution, and environmental robustness, particularly concerning temperature variations.
• Fiber Bragg Gratings (FBGs) offer potential for high-sensitivity sensing, but their application in two-dimensional inclination measurement requires novel configurations.

Purpose of the Study:

• To introduce a novel two-dimensional fiber-optic inclinometer.
• To achieve high sensitivity and resolution in simultaneous tilt angle and direction measurements.
• To develop a temperature-insensitive sensing solution for inclination monitoring in challenging environments.

Main Methods:

• Fabrication of a two-dimensional inclinometer using crisscrossed arrays of etched chirped fiber Bragg gratings (CFBG).
• Modification of CFBGs by etching away cladding to expose the evanescent wave, enhancing sensitivity to refractive index changes.
• Interrogation of reflection spectra to analyze superposition peaks induced by partial immersion in liquid, enabling simultaneous angle and direction deduction.

Main Results:

• Achieved a high resolution of 0.003° for tilt angle measurement.
• Demonstrated a resolution of 0.00187 rad for tilt direction measurement.
• The sensor exhibited temperature insensitivity due to its unique sensing mechanism.

Conclusions:

• The proposed fiber-optic inclinometer effectively measures two-dimensional tilt with high precision.
• The sensor's temperature insensitivity and robustness make it suitable for long-term monitoring in harsh conditions.
• This technology holds promise for applications requiring real-time feedback control of tilt angles.