Optical Soot Particle Sensor with Focused Laser Spot
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Solution Overview
Problem
Current soot particle sensors in vehicles struggle to accurately measure the number of small soot particles due to their small mass, which is critical for health impacts, and are unable to provide both mass and numeric concentrations effectively, especially in diesel and gasoline engines.
Innovation Solution
A soot particle sensor using a CW laser module with an optical element to focus laser light into a small spot, enabling detection of temperature radiation and chemical reactions, allowing for single particle measurement and rapid counting of soot particles, using cost-effective semiconductor lasers and photodiodes for enhanced precision and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-power nanosecond lasers are used for laser-induced incandescence, then detection sensitivity for small soot particles is improved, but device cost and complexity increase
Solution Approach 1:
The patent changes the laser operating parameters from nanosecond pulsed high-power mode to continuous wave low-power mode. By using a CW laser with power around 100 mW and focusing it through a high numerical aperture objective (NA > 0.5), the system achieves sufficient heating of soot particles without requiring expensive high-power laser systems. This parameter change resolves the contradiction by maintaining detection sensitivity while reducing device complexity and cost.
2Quantity of substance
If mass concentration measurement is used, then total soot mass is detected, but numeric concentration of small particles cannot be determined
Solution Approach 1:
The patent segments the measurement process into two distinct detection modes: mass concentration measurement for aggregated soot particles and numeric concentration measurement for individual small particles. The LII signal amplitude provides mass information, while the signal duration and particle trajectory analysis through the focused laser beam provide particle count information. This segmentation allows simultaneous determination of both mass and numeric concentrations, resolving the information loss problem.
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 measurement of both mass and numeric concentrations of soot particles, improving health monitoring in vehicles and other combustion processes by detecting even small particles with high sensitivity and speed, addressing the limitations of existing sensors.
Implementation Method 1
The soot particles are heated using a nanosecond pulse of a high-power laser to several thousand degrees Celsius, so that they emit significant temperature radiation
Implementation Method 2
The thermally induced light emission of the soot particles is measured using a light detector
Implementation Method 3
the optical element is configured to bundle parallel laser light originating from the laser module in the spot
Implementation Method 4
the detector is situated in the soot particle sensor in such a way that it detects radiation originating from the spot. The radiation may be temperature radiation
Data Source
AI summary
A soot particle sensor includes a laser module including a laser and a detector configured for the detection of temperature radiation. The soot particle sensor provides that the laser is configured to generate laser light, and the soot particle sensor includes an optical element situated in the beam path of the laser of the laser module, which is configured to bundle laser light originating from the laser module in a spot, and the detector is situated in the soot particle sensor so that it detects the radiation originating from the spot.