Optical Analyzer LED Noise Reduction via Wavelength Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical analyzers using LEDs as light sources face challenges in measurement accuracy due to temperature-dependent light emission, noise, and drift, which affect the linearity of absorption measurements, especially in high-absorbance regions.
Innovation Solution
Incorporating an optical filter in the optical path to block light within specific wavelength ranges where temporal changes in light intensity are significant, particularly outside the peak wavelength region, to reduce noise and drift, and using a bandpass filter to allow only a narrow range of wavelengths centered on the peak intensity while blocking stray light from the base portions of the emission spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an LED is used as a light source, then the cost is reduced and reliability is improved, but measurement accuracy deteriorates due to temperature-dependent light emission and noise
Solution Approach 1:
The patent extracts and removes the harmful wavelength components (shorter and longer than the peak wavelength) from the LED emission spectrum using optical filters. This separates the useful monochromatic light at the peak wavelength from the harmful broadband components, allowing the system to maintain LED advantages while achieving measurement accuracy comparable to conventional light sources
Solution Approach 2:
The patent applies local quality by selectively transmitting only the specific wavelength region at the peak wavelength while blocking other wavelength regions. The optical filters are designed to provide different transmission characteristics at different wavelength regions, creating a localized useful signal from the broader LED emission spectrum
2Manufacturing precision
If the peak width of LED emission spectrum is used directly, then the linearity of absorption improves, but noise and drift increase due to temporal changes in light intensity
Solution Approach 1:
The patent extracts only the peak wavelength component from the LED emission spectrum using optical filters, removing the broadband components that cause temporal intensity changes. This extraction process eliminates noise and drift while preserving the monochromatic characteristic needed for linear absorption
Solution Approach 2:
The patent segments the LED emission spectrum into distinct wavelength regions: the useful peak wavelength region and the harmful broadband regions. Optical filters are designed to selectively transmit the peak region while blocking other regions, achieving segmentation of the spectrum into useful and harmful components
3Measurement precision
If an optical filter is added to block unwanted wavelengths, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent uses inexpensive optical filters (such as interference filters or absorptive filters) that can be easily integrated into the optical path. These filters are relatively simple components compared to complex monochromators, providing effective wavelength selection at low cost and minimal complexity
Solution Approach 2:
The optical filters serve as intermediary components between the LED light source and the sample/detector system. These filters mediate the interaction by selectively transmitting only the desired peak wavelength, acting as a simple yet effective wavelength selection mechanism without requiring complex mechanical or electronic control systems
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 measurement accuracy and linearity by minimizing noise and drift in detection signals, achieving results comparable to high-accuracy absorbance detectors without the need for a monochromator, while maintaining the cost-effectiveness and reliability of LED light sources.
Implementation Method 1
an optical filter is provided in an optical path from the light source to the detector, the optical filter blocking light within a range of wavelengths longer than the wavelength of a peak having the highest intensity in an emission spectrum of the light source
Implementation Method 2
a light-emitting semiconductor device is used as the light source
Implementation Method 3
LEDs have a comparatively narrow peak in their emission spectra
Implementation Method 4
introducing light obtained from the sample in response to the cast light into a detector
Data Source
AI summary
An optical filter 4 is placed in an optical path between a light source unit 1 using a deep ultraviolet LED as a light source and a sample cell 2. The optical filter 4 is a shortpass filter that allows passage of light of a main peak located within a deep ultraviolet region while blocking light of an unwanted peak located within a visible region. The temporal change in the amount of light of the unwanted peak is considerably greater than that of the main peak. The optical filter 4 blocks the former light whose amount considerably changes with time. As a result, the influence of the noise and drift originating from the LED on the detection signal obtained in a detector 3 is dramatically reduced, so that the analytical accuracy is improved.