Spectroscopic Sensor for Flat Sheet Measurement
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Solution Overview
Problem
Current optical sensors for the paper and plastics industries face challenges in measuring multiple characteristics of flat sheet products due to limitations in spectral range, spectral resolution, and signal-to-noise ratio, as well as the inability to cover the entire visible to mid-IR range with a single sensor.
Innovation Solution
A sensor apparatus combining one or more optical spectrometers with single channel filter and detector combinations to enhance resolution, signal-to-noise ratio, and spectral range capabilities, allowing for multiple measurements with a single compact and economical sensor package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical sensor is used to measure multiple characteristics of flat sheet products, then device complexity is reduced, but spectral range and measurement precision are insufficient
Solution Approach 1:
The sensor system is segmented into multiple independent detection channels, each dedicated to measuring specific spectral regions (visible, near-IR, mid-IR). Each channel includes its own light source, detector, and processing unit, allowing simultaneous measurement of multiple sheet properties without interference between measurements.
Solution Approach 2:
The sensor system achieves multi-functionality by integrating multiple spectral detection capabilities into a single unified sensor apparatus. The system can measure various sheet characteristics including moisture content, thickness, coating weight, and opacity by selectively activating different spectral channels, eliminating the need for multiple separate sensors.
2Adaptability or versatility
If spectral range is extended to cover visible to mid-IR, then measurement capability improves, but device complexity increases
Solution Approach 1:
The extended spectral range is achieved through segmentation into distinct spectral bands (visible, near-IR, mid-IR), with each band handled by a dedicated detection channel. This modular approach allows the system to cover a broad spectral range while keeping each individual channel relatively simple and manageable.
Solution Approach 2:
The sensor system adds a dimensional aspect by incorporating multiple spectral channels that operate simultaneously in different spectral regions. This multi-dimensional approach to spectral measurement allows comprehensive coverage from visible to mid-IR without requiring a single complex instrument to handle all wavelengths sequentially.
3Measurement precision
If multiple single channel detectors with filters are used to measure multiple components, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
Multiple single channel detectors with bandpass filters are merged into a unified sensor system where each detector channel is combined with dedicated light sources and signal processing circuits. This integration allows simultaneous measurement of multiple sheet components while sharing common structural elements, reducing overall system complexity compared to using separate sensors.
Solution Approach 2:
The sensor system achieves universality by designing each detection channel to be independently configurable for different spectral regions and measurement targets. The same basic channel architecture can be adapted to measure different sheet properties by changing the light source wavelength and detector sensitivity, eliminating the need for completely different sensors for each measurement type.
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 combination extends the spectral range and improves measurement accuracy and repeatability, enabling the simultaneous measurement of various properties across the visible, near-IR, and mid-IR spectra, addressing the limitations of existing sensors.
Implementation Method 1
IR radiation is partly absorbed, reflected and transmitted by the sample 110 depending on its various properties
Implementation Method 2
IR radiation is partly absorbed, reflected and transmitted by the sample 110
Implementation Method 3
A plurality of beam splitters arranged in series for splitting the radiation after the radiation interacts with the flat sheet product
Implementation Method 4
Each beam is directed to a separate bandpass filter 170 and 160, respectively, each of which is positioned and aligned immediately before detector 135 and 145, respectively. The bandpass filters 170 and 160 are configured to pass IR radiation at selected regions of the infrared spectrum
Implementation Method 5
Depending on the intensity of the radiation detected at the detector, the detector generates an analog electrical signal
Data Source
AI summary
A spectroscopic sensor for measuring flat sheet product is disclosed. The disclosed sensor uses a combination of spectrometers and single-channel detectors and filters together with a broadband source of illumination to optimally measure multiple properties of a flat sheet product. A spectrometer is used to measure over a spectral range where an easily configurable set of wavelength channels is needed and where the signal-to-noise ratios and spectral resolutions of the channels are consistent with the spectral range and number of pixels of the spectrometer; while one or more single channel detector and filter combinations are used to measure, with high signal-to-noise ratio, at specific wavelengths within or outside the spectral range of the spectrometer(s). Therefore, the single channel detectors can be used to complement the information provided by a spectrometer or to extend the working range of a spectrometer by providing single wavelength measurements anywhere in the visible, near-IR or mid-IR spectral regions.