Optical Particle Sensor Module Dual Beam Velocity Detection
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Solution Overview
Problem
Existing laser sensor modules for particle density detection are bulky and not suited for all applications, as they require a predefined particle flow direction and velocity, which limits their portability and accuracy in detecting small particles at varying velocities.
Innovation Solution
A laser sensor module using two measurement beams that enclose an angle between 10° and 160° to determine two independent velocity components, allowing for particle detection without a predefined flow direction and velocity, with a small numerical aperture to enable reliable detection in handheld devices like smartphones, and an evaluator that corrects for velocity dependencies and particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensing techniques use a measurement volume with known particle flow direction and velocity (e.g., using fan or MEMS mirror), then particle detection accuracy is improved, but device complexity and bulkiness increase
Solution Approach 1:
The patent changes the fundamental measurement parameters by using multiple measurement beams at different angles (10°-160°) instead of a single beam with controlled particle flow. This allows the system to measure both particle density and velocity components simultaneously, eliminating the need for mechanical particle flow control devices like fans or MEMS mirrors while maintaining measurement accuracy
Solution Approach 2:
The sensor module performs multiple functions simultaneously: it measures particle density, particle velocity, and particle flow direction using the same optical components. The evaluator processes signals from multiple beams to extract all these parameters, making the device universally applicable without requiring additional specialized components for each measurement type
2Measurement precision
If multiple measurement beams with angles between 10° and 160° are used to determine velocity components, then particle velocity measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement function by using multiple independent measurement beams at different angles, where each beam contributes to measuring a specific velocity component. The evaluator then integrates these segmented measurements to calculate the complete velocity vector, achieving accurate multi-dimensional velocity measurement without requiring a single complex optical system
Solution Approach 2:
The patent transitions from one-dimensional velocity measurement (single beam) to two-dimensional or three-dimensional velocity measurement by introducing multiple beams at different angular dimensions (10°-160°). This dimensional expansion allows simultaneous measurement of multiple velocity components, improving measurement accuracy while using simple optical components arranged at different angles
3Volume of moving object
If small numerical aperture optics are used to enable handheld device integration, then portability is improved, but particle detection sensitivity decreases
Solution Approach 1:
The patent uses multiple measurement beams as copies of the same optical measurement principle, where each beam provides redundant measurement information. This allows the system to compensate for the reduced sensitivity of small aperture optics by aggregating signals from multiple beams, maintaining detection capability in compact handheld devices
Solution Approach 2:
The patent changes the detection parameters by using multiple beams at different angles to measure both particle density and velocity. The evaluator uses these multiple parameters to calculate particle density, which compensates for the reduced signal strength from small aperture optics, enabling sensitive detection in portable devices
4Reliability
If the sensor is designed for reference velocity within predetermined velocity range, then measurement reliability is improved, but adaptability to varying velocities decreases
Solution Approach 1:
The patent makes the measurement system dynamic by using multiple measurement beams that can detect particles across a wide velocity range. The evaluator dynamically adjusts measurements based on the detected velocity components, allowing the system to maintain reliability across varying velocities rather than being fixed to a single reference velocity
Solution Approach 2:
The sensor module is designed with universal measurement capability to handle various velocity conditions. By measuring both particle density and velocity simultaneously using multiple beams, the system can adapt to different velocity ranges and provide reliable measurements across diverse operating conditions, not limited to a single reference velocity
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 reliable particle density detection with minimal error across a range of velocities, particularly in handheld devices, with improved accuracy and portability, capable of detecting small particles and providing particle density values like PM2.5 with an error of less than 20%.
Implementation Method 1
at least a first detector being adapted to determine a first interference or self-mixing interference signal
Implementation Method 2
at least a first detector being adapted to determine a first interference or self-mixing interference signal
Implementation Method 3
an optical arrangement being arranged to focus the first measurement beam to a first measurement volume
Implementation Method 4
an optical detector device having at least one detection surface that is struck by at least a portion of the optical radiation scattered at the at least one particle
Data Source
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AI summary
2016PF01329 39 ABSTRACT: 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'),5 an optical arrangement (150) being arranged to focus at least the first measurement beam (111') to a first measurement volume (161), the optical arrangement being further arranged to focus at least the second measurement beam (112 ') to a second measurement volume (162), wherein the optical arrangement is characterized by a first numerical aperture with respect to the first measurement beam (111') and a second numerical 10 aperture with respect to the second measurement beam (112'), wherein the first numerical aperture and the second numerical aperture are arranged to detect a predetermined minimum particle size at a reference velocity, wherein the reference velocity is chosen within a predetermined velocity range comprising the reference velocity, and wherein the first measurement beam (111') and the second measurement beam (112') mutually enclose an 15 angle between 10° and 160°, at least a first detector (121) being adapted to determine a first self-mixing interference signal of a first optical wave within a first laser cavity of the first laser (111), at least a second detector (122) being adapted to determine a second self- mixing interference signal of a second optical wave within a second laser cavity of the 20 second laser (111), an evaluator (140), wherein the evaluator (140) is adapted to receive detection signals generated by at least the first detector (121) and the second detector (122) in reaction to the determined self-mixing interference signals, wherein the evaluator (140) is further adapted to determine at least a first average velocity of particles detected by the first detector 25 (121) and at least a second average velocity of particles detected by the second detector (122) by means of the detection signals received in a predetermined time period, wherein the evaluator (140) is further adapted to determine at least a first number of particles based on the detection signals provided by the first detector (121) in the predetermined time period and at 2016PF01329 40 least a second number of particles based on the detected signals provided by the second detector (122) in the predetermined time period, and wherein the evaluator (140) is further adapted to determine a particle density based on an average particle velocity determined at least by means of the first average velocity and the second average velocity, at least the first number of particles and at least the second number of particles.5 The invention further relates to a method of particle density detection and a corresponding computer program product. The invention further relates to a mobile communication device (190) comprising such a laser sensor module (100). 10