Fiber Optic Sensor Broadband Spectral Analysis Papermaking
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Solution Overview
Problem
Current moisture sensors in papermaking processes have limited spectral resolution and wavelength range, restricting their application to measuring moisture and requiring elaborate calibration for different paper grades, which hinders efficient control of papermaking processes and increases off-specification product and paper breaks.
Innovation Solution
A sensor system utilizing a high brightness light source, such as fiber optic supercontinuum sources or multiplexed superluminescent light emitting diodes, coupled with a dispersive element for spectral analysis, allows simultaneous measurement of moisture, temperature, and cellulose content in paper, enabling robust calibration across various paper grades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional moisture sensors with limited spectral resolution are used, then the device complexity is reduced, but the measurement precision and adaptability across different paper grades deteriorate
Solution Approach 1:
The sensor system segments the spectral measurement into multiple discrete wavelength channels using a dispersive element (prism or grating) that separates the broadband light source spectrum into spatially resolved wavelength components. This allows high spectral resolution through physical separation of wavelengths rather than requiring complex electronic spectral analysis, thereby improving measurement precision while keeping the device structure relatively simple.
Solution Approach 2:
The sensor system uses a universal broadband light source (such as a halogen lamp or LED array) that can measure multiple parameters (moisture content, temperature, cellulose content) across different paper grades simultaneously. This multi-functional approach eliminates the need for separate specialized sensors for each parameter and paper grade, improving adaptability while avoiding the complexity of multiple dedicated measurement systems.
2Adaptability or versatility
If conventional sensors with narrow wavelength range are used, then the ease of manufacture is improved, but the adaptability to measure multiple parameters and paper grades deteriorates
Solution Approach 1:
The sensor system merges multiple measurement functions (moisture sensing, temperature sensing, cellulose sensing) into a single integrated sensor head that uses one broadband light source and one dispersive element. This combination allows the system to access the entire visible to near-infrared spectrum for multiple parameters simultaneously, improving adaptability across paper grades while avoiding the manufacturing complexity of assembling multiple separate sensors and light sources.
3Measurement precision
If elaborate calibration procedures are used for different paper grades, then the measurement precision for specific grades is improved, but the productivity and time required for calibration deteriorate
Solution Approach 1:
The sensor system uses parameter changes in the spectral response patterns across different wavelength channels to distinguish between paper grades. By measuring the spectral reflectance or transmittance at multiple wavelengths and analyzing the pattern changes rather than requiring grade-specific calibration curves, the system achieves high measurement precision for various paper grades without time-consuming elaborate calibration procedures for each grade.
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 solution provides accurate, simultaneous measurement of multiple parameters, enhancing process control, reducing off-specification products, and minimizing paper breaks by offering improved spectral resolution and range, allowing for more robust calibrations and better control of papermaking processes.
Implementation Method 1
a high brightness light source; means for generating detection radiation from the high brightness light source
Implementation Method 2
a dispersive element that is disposed in the detection beam path
Implementation Method 3
a fiber optic radiation delivery system that delivers the detection radiation to an optical head
Implementation Method 4
a detector operable to receive and measure light from the second fiber optic radiation delivery system
Data Source
AI summary
Fiber optic sensors employ a high brightness light source such as a fiber optic supercontinuum source, multiplexed superluminescent light emitting diodes, or a broadband tunable laser diode. Light is delivered to the measurement location via fiber optics and sensor optics directs infrared radiation onto material the being monitored that is located in a hostile environment. A disperse element is positioned in the detection beam path in order to separate the wavelengths and to perform spectral analysis. A spectral analysis of the radiation that emerges from the sheet yields information on a plurality of parameters for the material. For papermaking applications, the moisture level, temperature and cellulose content in the paper can be obtained.