Particle Counting System with Optical Density Compensation
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Solution Overview
Problem
Existing optical particle counters face challenges in accurately detecting sub-micron and nano-sized particles due to low light source utilization, complex optical structures, and reduced sensitivity and resolution, especially when particles pass through the detection area at angles other than the center.
Innovation Solution
A particle counting method and system that generates a light channel with a normally distributed optical density, compensates pulse signal amplitudes based on the distance from the center, and converts these signals into digital signals for accurate particle sizing, using a semiconductor laser, collimating lens, photoelectric detector, and micro control unit to ensure uniform optical density and improved detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light source is converted into a line spot through optical components to ensure uniform distribution in the detection area, then the sensitivity and resolution of detection are improved, but the optical structure becomes complicated and the light source utilization rate decreases
Solution Approach 1:
The patent extracts and removes the complex optical components (convex lenses, cylindrical mirrors, etc.) from the detection system. Instead of using multiple optical elements to shape the light, the invention directly uses a line-shaped laser beam as the light source, eliminating the need for these intermediate optical shaping components and simplifying the overall optical structure while maintaining detection precision.
Solution Approach 2:
The line-shaped laser beam serves multiple functions simultaneously: it provides uniform illumination across the detection area, defines the detection volume, and eliminates the need for separate optical shaping components. This multi-functional approach reduces system complexity while maintaining or improving detection capabilities.
2Measurement precision
If the light source is converted into a line spot to distribute light uniformly in the detection area, then the sensitivity and resolution are improved, but the light source utilization rate decreases
Solution Approach 1:
The patent eliminates the intermediate optical conversion step that causes energy loss. By directly using a line-shaped laser beam without converting through optical components, the system avoids losses associated with reflection, absorption, and scattering in these components, thereby improving light source utilization rate while maintaining uniform light distribution.
Solution Approach 2:
The line-shaped laser beam inherently provides the desired uniform light distribution pattern without requiring additional optical shaping components. The laser source itself performs the function of creating the detection volume and illuminating the particles uniformly, eliminating energy losses in intermediate optical conversion stages.
3Use of energy by moving object
If a circular spot is used to improve light source utilization and increase scattered light intensity, then the sensitivity is improved, but the optical density distribution becomes uneven and reduces measurement precision
Solution Approach 1:
The patent employs an asymmetric line-shaped light spot instead of a symmetric circular spot. This asymmetric geometry provides uniform optical density distribution across the detection area, ensuring that particles at different positions experience consistent illumination conditions, thereby maintaining high measurement precision while achieving good light source utilization.
Solution Approach 2:
The line-shaped laser beam creates a detection volume with locally uniform optical density distribution. Each region within the detection volume receives consistent light intensity, ensuring that particle detection resolution is maintained across the entire detection area, unlike the non-uniform illumination provided by circular spots.
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 method enhances sensitivity and resolution, allows for universal particle detection regardless of entry angle, and simplifies the optical path structure, improving the light source utilization and accuracy of particle sizing across various sizes.
Implementation Method 1
generating a light channel for detecting particles
Implementation Method 2
acquiring optical signals scattered by the particles passing through the light channel
Implementation Method 3
converting the optical signals into pulse signals
Data Source
AI summary
The present disclosure relates to a particle counting method and system. The particle counting method, comprises: obtaining distances between positions closest to a centers of a light channel in paths along which particles pass through the light channel and the centers of the light channel; according to an optical density distribution of the light channel, compensating amplitudes of the pulse signals of the particles when passing through the positions closest to the centers of the light channel in the path along which the particles pass through the light channel such that the compensated amplitudes of the pulse signals of the particles are equal to amplitudes of pulse signals of the particles with the same particle diameters when passing through the centers of the light channel; screening and counting the particles according to the compensated amplitudes of the pulse signals to realize counting of particles with respective particle sizes.