Evanescent Wave Sensor Head With Protective Flange
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Solution Overview
Problem
Evanescent wave optical fiber sensors are prone to mechanical fragility due to their small diameter, leading to high maintenance costs as the sensitive curved part often breaks, requiring frequent replacement.
Innovation Solution
A head for the sensor featuring a curved optical fiber section protected by a flange system with a stud and flow conduit, allowing external liquid medium flow and mechanical protection while maintaining contact with the environment, and comprising machinable ribs and planes for secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the curved part is left exposed to contact with the external medium, then detection sensitivity is improved, but mechanical fragility increases leading to frequent breakage
Solution Approach 1:
A protective sheath made of flexible material is applied over the curved part of the optical fiber. This sheath acts as a mechanical barrier against external aggressions while maintaining the flexibility needed for the fiber to function. The sheath protects the fragile curved section from breakage during handling and operation, directly resolving the contradiction between mechanical robustness and environmental exposure.
Solution Approach 2:
The protective sheath is applied in advance to the curved part before the fiber is deployed to the external medium. This pre-protection approach ensures that the vulnerable curved section is cushioned against mechanical damage from the outset, preventing breakage before it occurs while allowing the fiber to maintain its detection capabilities.
2Reliability
If the curved part is protected against mechanical damage, then reliability is improved, but contact with the external medium may be compromised
Solution Approach 1:
The protective sheath is designed with sufficient flexibility that it does not prevent the curved part from making contact with the external medium. The sheath material allows the fiber to bend and conform to the measurement interface while providing mechanical protection, thus maintaining operational capability while improving reliability.
Solution Approach 2:
The protective sheath is applied selectively only to the curved part of the fiber where mechanical protection is needed, rather than covering the entire fiber length. This localized protection approach ensures that the curved section is protected while other parts of the fiber remain exposed and functional for light transmission and environmental interaction.
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
Enhances the mechanical robustness of the curved part, reducing the likelihood of breakage and associated maintenance costs while ensuring effective contact and signal transmission.
Implementation Method 1
an optical fiber that allows the propagation of infrared light at at least one infrared wavelength and generates outward evanescent waves to detect infrared signatures of an external medium
Implementation Method 2
certain wavelengths of the wave are absorbed by the external medium
Data Source
AI summary
The present invention relates to a head (500) for a sensor comprising two sections of optical fibre enabling the propagation of infrared light having at least one infrared wavelength and generating evanescent waves toward the outside in order to detect infrared signatures of an external medium, said head (500) comprising: an optical fibre forming a curved portion (15) for connecting the two sections of fibre, and for engaging with the external medium so as to detect the infrared signatures interfering with the propagation of the evanescent waves propagating along the fibre; and a means (504, 506) for protecting the curved portion (15) against external mechanical stress, while ensuring that a contact area (30) exists between the external medium and said curved portion (15).