Particulate Matter Sensor Using TIR Lenses for Orthogonal Beam Orientation
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Solution Overview
Problem
Existing particulate matter sensors for portable electronic devices face challenges in accurately measuring particulate matter concentration due to uncertainties in airflow direction and speed, particularly when using self-mixing interferometry, which requires complex gas flow control and alignment of multiple laser beams, making it difficult to achieve accurate measurements in compact, modular formats like smartphones and smart watches.
Innovation Solution
The implementation of three coherent or partially coherent light sources with total-internal-reflection (TIR) lenses that tilt beams to form an orthogonal basis in three-dimensional space, allowing for independent measurements of particulate matter flowing with gas, even in compact devices, by redirecting beams to converge at a common or multiple locations outside the device enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-mixing interferometry with fan-based airflow control is used to measure particulate matter, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts and removes the fan-based airflow control system from the sensor design. Instead of using a fan to move air through a sensing volume, the invention allows ambient air to flow naturally over the laser beams, eliminating the complex mechanical airflow control system while maintaining measurement capability
Solution Approach 2:
The patent transitions from a three-beam configuration requiring precise spatial alignment to a single-beam configuration with temporal analysis. By measuring frequency shifts over time as particles pass through the laser beam, the system achieves accurate particulate matter and wind speed measurements without requiring multiple aligned beams or controlled airflow
2Measurement precision
If multiple laser beams are aligned to form orthogonal basis for measurement, then measurement precision improves, but alignment difficulty and device complexity increase
Solution Approach 1:
The patent removes the requirement for multiple aligned laser beams by using a single-beam configuration. The orthogonal basis for wind speed and direction measurement is achieved through temporal analysis of frequency shifts rather than spatial arrangement of multiple beams, eliminating alignment difficulties
Solution Approach 2:
The patent replaces the mechanical alignment of multiple laser beams with a temporal measurement approach. Instead of physically arranging beams in orthogonal directions, the system uses time-series analysis of frequency shifts from a single beam to infer wind speed and direction, substituting mechanical precision with temporal resolution
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
This configuration enables accurate particulate matter concentration measurements with reduced errors, as the beams form an orthogonal basis, facilitating precise wind speed and direction inference, and is feasible in compact, portable devices without the need for bulky gas flow control systems.
Implementation Method 1
three total-internal-reflection (TIR) lenses arranged to redirect the three corresponding light beams into three corresponding directions that form an orthogonal basis in a three-dimensional space
Data Source
AI summary
Aspects of the subject technology relate to particulate matter sensors for electronic devices. A particulate matter sensor may include three lasers, three total-internal-reflection lenses, and three detectors for detecting changes in the operation of the three lasers due to the principles of self-mixing interferometry. The three total-internal-reflection lenses may use internally reflective surfaces to tilt the three beams into three corresponding directions that form an orthogonal basis in the three dimensional space, so that a gas flow speed can be determined while maintaining a small, modular form factor for implementation of the sensor in portable electronic devices.