Light-Absorbing Particle Concentration Measurement With One Photodetector
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Solution Overview
Problem
Existing methods for measuring the concentration of light-absorbing particles, such as black carbon, suffer from inaccuracies due to differences in light sources and detectors used in concentration and reference measurement paths, which are influenced by detector drift and moisture, leading to measurement errors.
Innovation Solution
Using the same photodetector for both concentration and reference measurement paths, with a light path switch to alternately measure light transmission through filter material with and without light-absorbing particles, and employing a pre-filter to separate large particles, thereby reducing detector drift and moisture effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate photodetectors are used for concentration and reference measurement paths, then the device can simultaneously measure both paths, but measurement accuracy deteriorates due to detector drift and differences between detectors
Solution Approach 1:
The patent merges the function of two separate photodetectors into a single photodetector that sequentially measures both the concentration path and reference path. This eliminates detector drift and inter-detector variability, directly resolving the contradiction by sacrificing simultaneous measurement capability for improved measurement accuracy through a shared detection system.
Solution Approach 2:
The patent implements periodic switching between measuring the concentration path and the reference path using a single photodetector. By alternately directing light from both paths to the same detector in periodic intervals, the system maintains measurement capability for both paths while ensuring that detector characteristics remain consistent across measurements, thereby improving accuracy.
2Adaptability or versatility
If different light sources are used for concentration and reference measurement paths, then the device can operate independently in both paths, but measurement stability deteriorates due to light source variations and cross-sensitivities
Solution Approach 1:
The patent merges the light source function by using a single light source that serves both the concentration measurement path and the reference measurement path through optical switching. This eliminates variations between different light sources and reduces cross-sensitivities, directly improving measurement stability while maintaining the ability to measure both paths.
Solution Approach 2:
The single light source is designed to serve multiple functions by illuminating both measurement paths sequentially. The optical switching mechanism enables the same light source to be universally applied to both the concentration path and reference path, ensuring consistent illumination characteristics and eliminating the need for separate light sources.
3Measurement precision
If a single photodetector is used for both concentration and reference measurements, then measurement accuracy improves by reducing detector drift, but the device complexity increases due to light path switching mechanisms
Solution Approach 1:
The patent introduces a light path switching mechanism as an intermediary component that directs light from either the concentration path or reference path to the single photodetector. This intermediary element enables the use of a single detector for both measurements while managing the complexity through a dedicated switching component rather than requiring complex integration throughout the entire system.
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 approach enhances measurement accuracy by minimizing measurement differences and cross-sensitivities, allowing for precise determination of particle concentration with high long-term stability and reduced maintenance requirements.
Implementation Method 1
The particles are deposited in the filter material, thereby changing the light absorption of the filter material
Implementation Method 2
The change in light absorption is measured using a light source on one side and a photodetector on the other side of the filter material
Implementation Method 3
The transmission of light through filter material loaded with light-absorbing particles is measured
Data Source
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AI summary
The present invention relates to a method and a device (100) for measuring the concentration of light-absorbing particles. The device (100) is very simple and compact in design and enables a very accurate measurement of the particle concentration with high long-term stability and long maintenance-free operation.