Fibre Optic Cable with Alternating Strain Sections for Directional Acoustic Sensing

The patent applies local quality by creating alternating longitudinal sections with different strain transfer characteristics. Some sections are configured to transfer strain from the fibre to the acoustic wave (positive coupling), while adjacent sections transfer strain in the opposite direction (negative coupling). This local differentiation enables directional sensitivity without requiring complex external components, as each section's unique strain transfer property contributes to the overall directional detection capability.

The patent implements asymmetry by designing the fibre optic cable with non-uniform structure along its length. The alternating positive and negative coupling sections create an asymmetric strain distribution pattern when exposed to acoustic waves from different directions. This asymmetric response allows the sensing system to distinguish between waves incident from opposite directions, resolving the directional ambiguity present in conventional uniform fibre structures.

The patent applies segmentation by dividing the fibre optic cable into multiple longitudinal sections, each with distinct strain transfer characteristics. These segmented sections are arranged in an alternating pattern along the fibre length, creating a modular structure that balances manufacturing feasibility with functional performance. The segmentation allows directional sensitivity to be achieved through systematic variation of section properties rather than through complex continuous variations.

The patent implements parameter changes by systematically varying the strain transfer characteristics along the fibre length. The alternating sections have different coupling parameters (positive vs. negative strain transfer), creating a periodic modulation of the fibre's mechanical response. This parameter variation enables directional sensitivity while maintaining a regular, manufacturable structure that can be produced using standard fibre drawing techniques with controlled variations.

The patent applies merging by integrating the directional sensing functionality directly into the fibre optic cable structure itself. The alternating positive and negative coupling sections are combined within a single cable assembly, eliminating the need for separate directional sensing components or multiple fibres. This merging approach achieves directional sensitivity through the inherent mechanical properties of the cable structure rather than through complex external systems.

The patent implements universality by designing the fibre optic cable to simultaneously perform acoustic wave detection and directional determination using the same sensing mechanism. The alternating coupling sections enable the single fibre to detect both the presence and direction of acoustic waves, providing multi-functional capability without requiring additional specialised components. This universal approach enhances measurement precision while avoiding the complexity of separate directional sensing systems.