Circular Array Fiber-Optic Sub-Sensor for Large-Area Bubble Observation, Part I: Design and Experimental Validation...

Area of Science:

• Oceanography
• Optical Engineering
• Fluid Dynamics

Background:

• Accurate measurement of microbubbles is crucial for understanding ocean surface processes.
• Existing methods for microbubble detection have limitations in scale and resolution.

Purpose of the Study:

• To propose and validate a novel buoy-type bubble sensor (BBS) for large-scale microbubble measurement.
• To design and test a fiber-optic sub-sensor for enhanced microbubble detection.

Main Methods:

• Theoretical modeling and experimental validation of a quartz fiber-optic sensitive unit.
• Fabrication of a prototype array element with a 90° cone angle.
• Feasibility experiments for static and dynamic two-phase (gas/liquid) identification.

Main Results:

• Optimal cone angle for fiber-optic units determined to be between 45.2° and 92°.
• Static identification showed an order of magnitude difference in optical power between gas and liquid.
• Dynamic sensing demonstrated measurable optical power variations (13.4–29.3 nW) for microbubble detection.

Conclusions:

• The proposed buoy-type bubble sensor integrates panoramic imaging with a fiber-optic array for improved microbubble measurement.
• Fiber-optic probes configured as arrays can overcome resolution limitations of current imaging techniques.
• This technology holds promise for advancing oceanographic research and monitoring.