Hydrophone Static Pressure Compensation via Filtered Optical Transduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydrophone systems face challenges such as bulkiness, complexity, and difficulty in depth pressure compensation, leading to saturation and reduced detection of dynamic pressure signals due to the much larger static pressure in underwater environments, which complicates the deployment and maintenance of underwater acoustic sensors.
Innovation Solution
A hydrophone system that includes a sensor providing electrical signals indicative of both static and dynamic pressures, with a filter to separate and output only the dynamic pressure component, and a transducer connected to a distributed feedback laser in a fibre optic cable to convert the filtered signal into an optical output, allowing for effective depth compensation and reduced bulkiness through passive circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fibre optic technology is used in hydrophones to reduce bulkiness and complexity, then the device size and complexity are reduced, but depth pressure compensation becomes more difficult due to the large static pressure affecting optical equipment
Solution Approach 1:
The patent extracts and removes the static pressure component from the optical signal by using a reference fibre that experiences the same static pressure but not the dynamic acoustic pressure. The differential measurement between the sensing fibre and reference fibre isolates only the dynamic pressure component, effectively filtering out the overwhelming static pressure effect.
Solution Approach 2:
The patent introduces a reference fibre as an intermediary element that mediates the measurement process. This reference fibre experiences the same environmental conditions (static pressure, temperature) as the sensing fibre but is isolated from the acoustic pressure. By comparing the two fibres, the system automatically compensates for environmental effects without requiring complex active instrumentation.
2Reliability
If multiple optical fibres and fibre couplings are used in fibre optic hydrophones, then optical sensing capability is achieved, but the equipment becomes bulky and complex
Solution Approach 1:
The patent merges the sensing and reference fibres into a single integrated optical path that shares common components (light source, couplings, detectors). By combining multiple measurement channels into a unified system with shared infrastructure, the patent reduces overall complexity while maintaining the reliability of optical sensing capability.
Solution Approach 2:
The patent creates a universal optical measurement system where a single light source, set of couplings, and detection circuitry serve multiple fibres (sensing and reference). This multi-functional approach eliminates the need for separate dedicated components for each fibre, significantly reducing equipment bulkiness and complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively filters out static pressure components, enhancing the detection of dynamic pressure signals, reducing the need for external power sources, and enabling the use of multiple sensors in a single optical channel, thus improving sensitivity and deployment ease.
Implementation Method 1
a filter electrically connected to the sensor so as to receive the electrical signal, filter out the first component, and output a filtered electrical signal indicative of substantially only the second component
Implementation Method 2
a transducer electrically connected to the filter, the transducer being responsive to the second component for acting upon a distributed feedback laser in a fibre optic cable so as to convert the filtered electrical signal into a corresponding strain on the distributed feedback laser
Implementation Method 3
the distributed feedback laser provides an optical output signal corresponding to the strain and hence indicative of the dynamic pressure
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A hydrophone (10) for immersion in a liquid body defining a pressure is disclosed The hydrophone (10) includes a sensor (11) for providing an electrical signal indicative of the pressure; and a transducer (12) electrically connected to the sensor (11). The transducer (12) acts upon a fibre optic cable (15) so as to convert the electrical signal into a corresponding optical output signal for transmission within the fibre optic cable (15). The liquid body defines a depth-dependent static pressure and a dynamic pressure and the sensor (11) provides an electrical signal having a first component indicative of the static pressure and a second component indicative of the dynamic pressure. A filter (16) is electrically connected to the sensor (11) so as to receive (he electrical signal, filter out the first component, and output to the transducer (12) a uttered electrical signal indicative of substantially only the second component.