Thinned Optical Fiber Pressure Sensing Without Bragg Gratings
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Solution Overview
Problem
Existing pressure measurement devices, particularly vacuum pressure sensors using fiber optic Bragg gratings, are complex, costly, and limited in accuracy due to the need for multiple lasers and the inclusion of metallic elements and Bragg gratings within the optical fiber, making them difficult to implement and design.
Innovation Solution
A pressure measurement device utilizing an optical fiber with a thinned portion, a single laser for both heating and interrogation, and a processing unit to measure backscattered waves for temperature variation, eliminating the need for Bragg gratings and metallic elements, and allowing for simpler, more compact, and cost-effective operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bragg gratings and metallic elements are inserted into the optical fiber, then pressure measurement functionality is achieved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent removes the Bragg grating and metallic layer from the optical fiber structure, keeping only the thinned portion. This extraction eliminates the complex manufacturing processes required for inserting and positioning these elements while maintaining pressure sensing capability through thermal effects on the thinned fiber section.
Solution Approach 2:
The optical fiber is thinned only in a specific localized section rather than modifying the entire fiber. This local modification creates the necessary thermal sensitivity for pressure measurement while preserving the standard fiber structure elsewhere, simplifying manufacturing compared to global modifications.
2Measurement precision
If multiple lasers are used for heating and interrogation, then measurement accuracy is improved, but device compactness and implementation simplicity deteriorate
Solution Approach 1:
A single laser source is used to perform both heating and interrogation functions by emitting optical waves at different powers. The same laser that heats the thinned fiber section also provides the reference wave for measuring backscattered signals, eliminating the need for separate laser systems and reducing overall device complexity.
Solution Approach 2:
The heating laser and interrogation laser are merged into a single laser source. The laser emits optical waves that serve dual purposes: heating the fiber during measurement and providing the reference signal for interrogation, thereby simplifying the system architecture while maintaining measurement precision.
3Measurement precision
If Bragg gratings are used for refractive index measurement, then pressure information can be retrieved, but manufacturing cost and design complexity increase
Solution Approach 1:
The Bragg grating is completely removed from the optical fiber structure. Instead of fabricating and inserting complex grating patterns, the patent uses a simple thinned fiber section that can be manufactured using standard fiber drawing processes, dramatically reducing manufacturing complexity and cost.
Solution Approach 2:
The patent changes the physical parameter of the optical fiber by thinning it to a specific diameter range (1-10 micrometers) rather than modifying its optical structure with gratings. This parameter change creates the necessary thermal sensitivity for pressure measurement while using simpler, more cost-effective manufacturing methods.
4Temperature
If metallic layers are added around the fiber, then thermal effects are enhanced, but device simplicity and cost-effectiveness are reduced
Solution Approach 1:
The metallic layer is removed from the optical fiber structure. The patent achieves sufficient thermal effects by thinning the fiber itself, eliminating the need for additional metallic components and their associated manufacturing complexity and cost.
Solution Approach 2:
The fiber is thinned only in the specific section where thermal effects are needed for pressure measurement, rather than coating the entire fiber with metal. This localized modification provides the necessary thermal sensitivity while maintaining overall structural simplicity.
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 solution provides a simpler, more cost-effective, and accurate pressure measurement by using a single laser for thermal excitation and interrogation, enhancing thermal effects and signal-to-noise ratio, facilitating easier implementation and adaptability in various environments.
Implementation Method 1
a laser, called a heating laser, arranged to emit an optical wave, called a heating wave, in the thinned portion
Implementation Method 2
a measuring means comprising a sensor arranged to measure a backscattered optical wave from an optical wave, called an interrogation wave, and originating from the thinned portion
Data Source
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AI summary
The invention relates to a pressure-measuring device (200) comprising: - an optical fibre (100) comprising a thinned portion (102), - a laser (202), called the heating laser (202), arranged to emit an optical wave, called the heating wave (204), into the thinned portion (102), - a measuring means (206) comprising a sensor (209) that is arranged to measure a backscattered optical wave (208) that is generated by an optical wave (210), called the interrogation wave (210), and that originates in the thinned portion (102) of the optical fibre (100), and - a processing unit (212) arranged and/or programmed to measure a pressure of a fluid, preferably a gas, encircling the thinned portion (102), on the basis of the measurement of the backscattered wave (208).