No-Core Fiber Speckle Correlation Refractive Index Sensor
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Solution Overview
Problem
Existing refractive index sensing systems are complex and expensive, requiring costly equipment to measure refractive index shifts in spectral peaks.
Innovation Solution
A low-cost optical refractive index measuring system utilizing a no-core optical fiber sensing module sandwiched between single-mode and multi-mode fibers, which uses speckle correlation to determine refractive index based on coherent light interaction and image analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional refractive index sensing methods (FBG, LPG, SPR, FPI) are used, then measurement precision is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent uses a no-core optical fiber that copies the speckle pattern from the surrounding liquid environment. Instead of measuring spectral peak shifts as in traditional methods, the system captures and analyzes specklegram images that replicate the refractive index information in a visually detectable format, simplifying the measurement system while maintaining precision
Solution Approach 2:
The patent replaces complex optical spectral analysis systems with a simpler image-based detection system. By substituting spectral peak measurement equipment with digital image capture and processing, the system achieves refractive index measurement with reduced device complexity and lower manufacturing costs
2Measurement precision
If traditional refractive index sensing methods are used, then measurement precision is achieved, but manufacturing cost increases
Solution Approach 1:
The no-core optical fiber sensing module uses a simple biconical fiber structure that can be manufactured at low cost. The design accepts that the fiber is a consumable sensing element that can be replaced, significantly reducing manufacturing costs compared to expensive spectral analysis equipment while maintaining measurement precision through specklegram analysis
3Measurement precision
If no-core optical fiber with biconical structure is used, then sensitivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves high sensitivity by changing the geometric parameters of the no-core fiber, specifically creating a biconical structure with varying diameter along its length. This parameter change enhances the interaction between light and the surrounding liquid, improving sensitivity without requiring extremely tight manufacturing tolerances on the overall device
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 provides a simple, sensitive, and cost-effective method for refractive index measurement, leveraging specklegram analysis to accurately determine refractive indices with high sensitivity and low manufacturing difficulties.
Implementation Method 1
an optical refractive index measuring system utilizing a refractive index sensing module and specklegram to measure refractive index based on speckle correlation
Implementation Method 2
uses speckle correlation to determine refractive index based on coherent light interaction and image analysis
Data Source
AI summary
An optical detection system for measuring a refractive index of a liquid analyte comprising a light transmitting assembly fiber, which includes a single-mode fiber, an optical fiber sensing module and a multi-mode fiber. The optical detection system is configured to emit a coherent light beam to one end of the assembly fiber; and a detector is configured to capture a specklegram from an exit end of the assembly fiber. When the optical detection system is in operation, the optical fiber sensing module is configured to be submerged into the liquid analyte. By analyzing the correlation between the specklegram corresponding to the liquid analyte and the reference specklegram, the refractive index of the liquid analyte can be obtained.