Movable Tip Fiber Optic Probe for Accurate Temperature Sensing
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Solution Overview
Problem
Fiber optic temperature sensors face challenges in achieving accurate measurements due to difficulties in calibrating the sensor to account for temperature differences between the sensing material and the target surface, as well as issues with mechanical stress and poor contact between the sensor tip and the surface.
Innovation Solution
The design of a fiber optic temperature sensing probe that includes a probe shaft with a first portion and a ferrule with a second projection, which cooperate to prevent uncoupling, along with a biasing member to encourage displacement between the ferrule and the probe shaft, ensuring secure contact with the target surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensing tip is rigidly aligned with the target surface, then the mechanical structure is simple and stable, but poor contact between the surfaces occurs preventing flush contact, reducing heat transfer rate and introducing thermal resistance
Solution Approach 1:
The sensing tip is made movable relative to the probe shaft through a biasing member (spring), allowing dynamic adjustment of the tip's position. This enables the tip to achieve flush contact with the target surface while maintaining mechanical stability through the biasing force, resolving the contradiction between contact quality and structural simplicity.
2Strength
If the sensing tip is rigidly fixed to the tube using bonding or mechanical structure, then the mechanical strength is high, but undesirable stresses are created on the components during installation and use
Solution Approach 1:
The probe is divided into separate components (probe shaft, ferrule, sensing tip) that can be assembled and disassembled. The biasing member allows the sensing tip to be securely held while permitting controlled movement, reducing stress concentration that would occur with rigid bonding while maintaining adequate mechanical strength during installation and operation.
Solution Approach 2:
The biasing member (spring) is pre-loaded to provide a cushioning effect that absorbs mechanical stresses during installation and operation. This pre-compression allows the sensing tip to maintain secure contact while protecting components from stress-related damage, resolving the contradiction between strength and stress reduction.
3Reliability
If the tube is made resistant to high temperatures and corrosion, then the probe can withstand harsh environments, but material selection becomes challenging and device complexity increases
Solution Approach 1:
The probe is segmented into components that can be made from different materials optimized for specific functions. The tube can be made from materials resistant to high temperature and corrosion, while other components use materials optimized for their specific requirements, simplifying overall material selection while maintaining environmental resistance.
4Measurement precision
If the sensing tip is positioned close to the target surface, then the temperature measurement accuracy is improved, but mechanical stress on the tip increases
Solution Approach 1:
The sensing tip is positioned close to the target surface through controlled displacement enabled by the biasing member. This dynamic positioning allows the tip to maintain optimal proximity for accurate temperature measurement while the biasing force prevents excessive mechanical stress by allowing controlled movement and compliance.
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
This configuration enhances the accuracy of temperature measurements by maintaining consistent contact and reducing thermal resistance, while also addressing mechanical stress and installation challenges.
Implementation Method 1
optical fiber(s) which can deliver light to a sensing material (e.g., phosphor)
Implementation Method 2
The light illuminates the phosphor which, in turn, luminesces. The temperature of the phosphor can be determined by observing the changes in certain characteristics of the emitted light.
Implementation Method 3
a biasing member connected to, and encouraging displacement between, the ferrule and the first portion
Data Source
AI summary
A fiber optic temperature sensing probe is described. The probe includes a probe shaft comprising a first portion comprising a first projection, and a cavity for having a fiber optic cable positioned therein. The probe includes a ferrule comprising a second projection, the second projecting cooperating with the first projection to prevent the ferrule and probe shaft from uncoupling from an assembled configuration. The probe includes a biasing member connected to, and encouraging displacement between, the ferrule and the first portion, The probe includes a sensing element positioned at a distal end of the ferrule and proximate to a surface to be measured, the sensing element configured to interact with light received from the fiber optic cable to measure a temperature of the surface to be measured.