Self-Referencing LED Detection for Spectroscopy Drift Correction
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Solution Overview
Problem
Conventional spectroscopy systems require complex and expensive equipment for full wavelength coverage, which is unnecessary for applications requiring single or limited wavelength detection, leading to inefficiencies and inaccuracies in measurements.
Innovation Solution
A self-referencing LED-based detection system using multiple LEDs emitting at different wavelengths, coupled into a single optical fiber for stable and consistent light output, with a reference photodiode for automatic correction of LED drift and stray light, allowing precise measurements in spectroscopy applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional spectrometers with broad wavelength coverage are used, then measurement flexibility and adaptability are improved, but device complexity and cost increase significantly
Solution Approach 1:
The system segments the broad spectrum requirement into multiple discrete wavelength channels, each handled by a dedicated LED source. Instead of using a single complex broadband source with monochromators, the patent divides the spectral coverage into specific wavelength bands (e.g., UV, visible, NIR) with each band served by appropriate LED elements, thereby simplifying the overall system architecture while maintaining multi-wavelength capability
Solution Approach 2:
The patent creates a universal detection platform that can handle multiple wavelengths through a single integrated detector and common optical path. The system uses a multi-channel LED array where each LED type serves multiple functions: wavelength-specific excitation, internal reference for drift correction, and compatibility with the same sample cell and detector, eliminating the need for separate systems for each wavelength range
2Device complexity
If single wavelength LED detection is used, then device complexity is reduced, but measurement accuracy deteriorates due to LED drift and stray light
Solution Approach 1:
The patent introduces an intermediary reference detection channel that measures the actual LED output intensity independently of the sample. This reference channel acts as a mediator between the LED source and sample measurement, providing real-time correction data that compensates for LED drift and stray light effects. The system uses this intermediary measurement to calculate corrected absorbance values, thereby maintaining high precision without increasing overall system complexity
Solution Approach 2:
The system implements feedback through continuous monitoring of LED output by the reference photodiode. The measured reference intensity is fed back into the calculation algorithm to dynamically adjust and correct the sample absorbance measurements. This feedback mechanism automatically compensates for temporal drift in LED intensity, ensuring measurement accuracy is maintained over time without requiring manual calibration
3Measurement precision
If multiple LEDs with different wavelengths are used, then measurement precision is improved through multi-wavelength detection, but device complexity increases
Solution Approach 1:
The patent merges multiple LED light sources into a single integrated optical assembly with a common mounting structure, electrical connection system, and optical coupling interface. The different wavelength LEDs are arranged in a compact array that shares common optical elements including the sample cell holder, detector positioning, and control electronics, thereby reducing device complexity despite using multiple wavelength sources
Solution Approach 2:
The system uses periodic switching of different wavelength LEDs rather than having all LEDs continuously active. The control system sequentially activates specific LED wavelengths based on the measurement requirements, allowing the same optical path and detector to serve multiple wavelength functions over time. This periodic activation reduces the complexity of simultaneous multi-wavelength optical paths while maintaining the capability for multi-wavelength measurements
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 precise and stable measurements with reduced spectral bandwidth, increasing the dynamic range and eliminating signal drift, enabling accurate absorbance detection with improved accuracy and reduced costs compared to traditional spectrometers.
Implementation Method 1
measuring their output with a reference detector
Implementation Method 2
coupling each of them into an optical fiber and coupling these fibers into a single fiber of large diameter for mixing their emission spectra
Implementation Method 3
Absorption spectroscopy uses the range of electromagnetic spectra in which a substance absorbs
Implementation Method 4
the amount of absorption can be related to the sample concentration through the Beer-Lambert law
Implementation Method 5
LEDs have long been used as quasi-monochromatic light sources
Data Source
AI summary
A light emitting diode (LED) based detection system is employed for spectroscopy based applications. LEDs are used as monochromatic light sources for applications at specific and pre-defined wavelengths. Spectrographic information is generated using LEDs of different wavelengths ranging from 260 nm to 1400 nm. Multiple wavelength information is generated by coupling light from each LED into an intensity and mode mixing fiber bundle. A dual beam approach of using a reference and a sample photodiode ensures automatic drift correction. Interference filters at the LED input fiber reduce the spectral bandwidth of the monochromatic light emission to a useful 10 nm bandwidth by cutting off the LEDs trailing emission distribution allowing for absorbance measurements similar to typical spectrometers.