Laser Sensor Module for Ultrafine Particle Detection
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Solution Overview
Problem
Current optical techniques are ineffective in detecting ultrafine particles with sizes of 300 nm or less due to reduced backscattering efficiency and signal amplitude, making it difficult to distinguish them from noise.
Innovation Solution
A laser sensor module that performs self-mixing interference measurements with adjustable sensitivities to detect particle sizes of 300 nm or less, using a calibration factor to eliminate signals from larger particles and enhance detection of smaller ones, employing semiconductor lasers, photodiodes, and optical devices with high numerical apertures to improve sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If optical techniques are used to detect ultrafine particles, then particle detection capability is improved, but detection precision deteriorates due to reduced backscattering efficiency and signal amplitude
Solution Approach 1:
The patent employs adjustable sensitivity levels that can be dynamically changed during measurement. The sensor can switch between a first sensitivity level for detecting larger particles and a second sensitivity level for detecting smaller ultrafine particles, allowing optimal detection across different particle size ranges.
Solution Approach 2:
The patent changes the sensitivity parameter of the optical detection system to overcome the reduced backscattering efficiency. By adjusting the sensitivity level and using calibration factors, the system compensates for the decreased signal amplitude from ultrafine particles, thereby improving measurement precision without sacrificing detection capability.
2Measurement precision
If sensitivity is increased to detect smaller particles, then detection capability for ultrafine particles is improved, but noise from larger particles increases
Solution Approach 1:
The system dynamically adjusts the sensitivity level based on the particle size being measured. When detecting ultrafine particles, the sensitivity is increased to the second level, while for larger particles, the sensitivity is reduced to the first level, thereby minimizing noise while maintaining detection capability.
Solution Approach 2:
The patent applies different sensitivity levels and calibration factors tailored to specific particle size ranges. The first sensitivity level and first calibration factor are optimized for larger particles, while the second sensitivity level and second calibration factor are optimized for ultrafine particles, allowing precise detection without excessive noise from other size ranges.
3Measurement precision
If multiple sensitivity levels are used to detect different particle sizes, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The evaluation unit automatically determines the appropriate sensitivity level and calibration factor based on the measurement requirements. The system self-adjusts between different sensitivity levels and applies the correct calibration factors without requiring manual intervention, thereby maintaining measurement precision while minimizing operational complexity.
Solution Approach 2:
The laser sensor module is designed with multi-functionality to handle different particle size ranges using a single device. By integrating multiple sensitivity levels and calibration factors into one sensor system, it eliminates the need for multiple separate sensors, thereby reducing overall device complexity while maintaining high measurement precision across different particle sizes.
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
Enables accurate detection of ultrafine particles by subtracting a second particle size distribution function multiplied by a calibration factor from the first, effectively eliminating noise from larger particles and enhancing the detection of smaller ones, allowing for precise measurement of particle sizes down to 50 nm or less.
Implementation Method 1
at least one detector which is adapted to determine a self-mixing interference signal of an optical wave within a laser cavity of the at least one laser, wherein the self-mixing interference signal is caused by reflected laser light reentering the laser cavity
Implementation Method 2
employing semiconductor lasers, photodiodes, and optical devices with high numerical apertures to improve sensitivity
Implementation Method 3
The effective reflection of a particle decreases drastically with particle size, not only due to their small size but additional due to a reduced backscattering efficiency given by the MIE scattering
Data Source
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AI summary
The invention describes a laser sensor module (100) for detecting ultra-fine particles (10) with a particle size of 300 nm or less, more preferably 200 nm or less, most preferably 100 nm or less, the laser sensor module (100) comprising: - at least one laser (110) being adapted to emit laser light to at least one focus region in reaction to signals provided by at least one electrical driver (130), - at least one detector (120) being adapted to determine a self-mixing interference signal of an optical wave within a laser cavity of the at least one laser (110), wherein the self-mixing interference signal is caused by reflected laser light reentering the laser cavity, the reflected laser light being reflected by a particle receiving at least a part of the laser light, - the laser sensor module (100) being arranged to perform at least one self- mixing interference measurement, - the laser sensor module (100) being adapted to determine a first particle size distribution function with a first sensitivity by means of at least one measurement result determined based on the at least one self-mixing interference measurement, the laser sensor module being further adapted to determine a second particle size distribution function with the second sensitivity, the second sensitivity being different from the first sensitivity, - the at least one evaluator (140) being adapted to determine a particle measure of the particle size of 300 nm or less by subtracting the second particle size distribution function multiplied with a calibration factor q from the first particle size distribution function. The invention further describes a corresponding method and computer program product. The invention enables a simple and low-cost particle detection module or particle detector based on laser self-mixing interference which can detect particles with a size of 100 nm or even less.