Airborne Particle Detection Using Homogeneous Laser Wavelengths
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Solution Overview
Problem
Existing measurement devices for detecting airborne particles suffer from insufficient precision in determining size and location due to limitations in light scattering techniques, particularly when using multiple lasers and photodetectors with different wavelengths, which introduce chromatic errors and impair accurate particle size and location determination.
Innovation Solution
A measurement device employing two time-amplitude modulated lasers with identical wavelengths and two photodetectors positioned to detect scattered light from both lasers, allowing for precise particle size determination by analyzing four independent scattering signals in two perpendicular planes, while eliminating chromatic effects and enabling accurate particle localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple lasers with different wavelengths are used to detect scattered light from particles, then the quantity of scattering signals increases, but chromatic errors are introduced that deteriorate measurement precision
Solution Approach 1:
The patent uses two lasers with identical wavelengths (e.g., both at 532 nm) instead of different wavelengths. This homogeneity in wavelength eliminates chromatic dispersion effects that would otherwise cause measurement errors when detecting scattered light from particles, while still providing multiple independent scattering signals for accurate particle size and location determination.
2Quantity of substance
If two lasers with different wavelengths are used, then more scattering signals are acquired, but particle location determination becomes impaired
Solution Approach 1:
The patent changes the wavelength parameter from different values to identical values for both lasers. This parameter change eliminates the chromatic aberration problem that impairs location determination, while maintaining the benefit of having two lasers provide four independent scattering signals (two per detector) for precise particle location and size measurement.
3Adaptability or versatility
If photodetectors are assigned to detect scattered light from specific lasers at different wavelengths, then selective detection is achieved, but detector saturation occurs and measurement precision decreases
Solution Approach 1:
By using identical laser wavelengths, the patent creates homogeneous detection conditions where both photodetectors receive scattered light at the same wavelength. This eliminates the need for wavelength-specific filters and prevents detector saturation, allowing both detectors to operate in their optimal linear range while maintaining selective detection capability through spatial arrangement.
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 significantly enhances the precision of particle size and location determination, avoiding detector saturation and providing accurate measurements for particles in the range of 1 μm to 100 μm, including pollens, spores, and other aerosols, with the ability to identify particle species through fluorescence or phosphorescence analysis.
Implementation Method 1
detection of laser light scattered in the laser beam intersection region by airborne particles contained in the laminar air flow
Implementation Method 2
first photodetector and a second photodetector positioned for the detection of laser light scattered
Data Source
AI summary
A measurement device and method for the detection of airborne particles. The device includes a nozzle designed to produce a laminar flow of air with a flow path beyond the nozzle, a first laser and a second laser being positioned for emitting time-amplitude modulated laser light with intersecting laser beams with a laser beam intersection region in a region of the air flow path, and two photodetectors positioned for the detection of laser light scattered in the laser beam intersection region by airborne particles contained in the laminar air flow. The lasers are designed for emission of time-amplitude modulated laser light of identical laser emission wavelength, and the photodetectors are positioned and designed each for the detection of scattered laser light from both lasers.