Self-Mixing Particle Sensor With Shared Detector Architecture
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Solution Overview
Problem
Existing laser sensor systems for particle density detection are complex, expensive, and require multiple self-mixing laser sensors to accurately measure particle velocity and density, especially in three-dimensional flows, which increases size and cost due to the need for movable parts and separate detectors for each laser.
Innovation Solution
A simplified laser sensor module using a common detector for multiple lasers emitting beams at fixed angles between 45° and 135°, allowing for the determination of particle density and velocity without differentiating between laser cavities, thereby reducing size, complexity, and cost, and enabling detection in both two- and three-dimensional particle flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple self-mixing laser sensors are used to measure particle velocity and density in three-dimensional flows, then measurement accuracy is improved, but device complexity and size increase due to the need for separate detectors for each laser
Solution Approach 1:
The patent combines multiple laser sources (at least two lasers) with a single common detector to form an integrated sensor system. The detector receives self-mixing interference signals from multiple laser cavities simultaneously, merging the detection function into one component. This reduces device complexity while maintaining the capability to measure particle velocity and density in three-dimensional flows through signal processing of the combined inputs.
Solution Approach 2:
The common detector serves multiple functions by detecting self-mixing interference signals from multiple different laser cavities. Instead of requiring dedicated detectors for each laser, the single detector universally handles signal detection from all laser sources, enabling the system to perform comprehensive particle measurement tasks with reduced component count.
2Adaptability or versatility
If multiple self-mixing laser sensors with movable parts are used to track particle flow, then measurement capability is improved, but device cost and mechanical complexity increase
Solution Approach 1:
The patent replaces mechanical systems (movable parts for tracking particle flow) with an optical system using multiple fixed laser sources arranged at specific angles. The adaptability to measure three-dimensional particle flow is achieved through the geometric arrangement of laser beams and optical detection rather than mechanical movement, eliminating complex mechanical components and reducing manufacturing cost.
Solution Approach 2:
The patent uses the spatial dimension by arranging multiple laser sources at different angles (with at least one angle between 45° and 135°) to create a multi-dimensional measurement capability. This geometric configuration enables the system to capture particle flow information in three-dimensional space without requiring mechanical movement, achieving versatility through spatial arrangement rather than mechanical complexity.
3Measurement precision
If separate detectors are assigned to each laser cavity, then signal detection accuracy is improved, but device size and cost increase
Solution Approach 1:
The patent merges the detection function for multiple laser cavities into a single common detector. The detector is positioned to receive self-mixing interference signals from multiple laser sources simultaneously, combining what would otherwise require multiple separate detectors. This integration maintains signal detection accuracy through proper optical coupling while significantly reducing the overall sensor module size.
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 solution enables accurate detection of particle density and velocity with reduced errors, allowing for compact and cost-effective implementation in various applications, including air quality monitoring, by using a single detector for multiple lasers and focusing elements to enhance signal strength.
Implementation Method 1
a self-mixing laser sensor module comprising at least a first laser being adapted to emit a first measurement beam and at least a second laser being adapted to emit a second measurement beam
Implementation Method 2
converges in the laser cavity the measuring beam radiation that has been back-scattered by an object to generate a self-mixing effect
Implementation Method 3
an optical device being arranged to redirect at least the first measurement beam such that the first measurement beam and the second measurement beam enclose an angle between 45° and 135°
Implementation Method 4
the optical device further comprises at least one focusing element associated to each measurement beam, wherein the at least one focusing element is arranged to focus the respective measurement beam to a focus region
Implementation Method 5
one detector being adapted to determine at least a first self-mixing interference signal of a first optical wave within a first laser cavity of the first laser and at least a second self-mixing interference signal of a second optical wave within a second laser cavity of the second laser
Data Source
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AI summary
The invention describes a laser sensor module. The laser sensor module comprises at least a first laser (111) being adapted to emit a first measurement beam (111') and at least a second laser (112) being adapted to emit a second measurement beam (112'). The laser sensor module further comprises an optical device (150) being arranged to redirect the first measurement beam (111') and the second measurement beam (112') such that the 5 first measurement beam (111') and the second measurement beam enclose an angle between 45° and 135°. The laser sensor module comprises one detector (120) being adapted to determine at least a first self-mixing interference signal of a first optical wave within a first laser cavity of the first laser (111) and at least a second self-mixing interference signal of a second optical wave within a second laser cavity of the second laser (112). This configuration 10 enables determination of an average velocity of the particles despite of the fact that it is not possible to determine the components of the velocity vector. The introduced error by means of statistical variations is acceptable because the number of detected particles scales with the cubic root of the particle velocity. The invention further describes a particle sensor (100) comprising such a laser sensor module, a corresponding method and computer program 15 product. The invention enables a simple and low-cost particle sensor (100) for detecting small particles based on laser self-mixing interference.