Compact Gas Sensor Using Curved Reflective Surfaces
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Solution Overview
Problem
Existing gas sensors face challenges in optimizing light wave attenuation and compactness while maintaining sensitivity, particularly in non-dispersive infrared (NDIR) sensors, which affect the accuracy and precision of gas composition analysis.
Innovation Solution
A gas sensor design featuring a series of curved reflective surfaces with specific focal configurations and eccentricities, forming a series of cones that extend the light path within a compact enclosure, allowing for multiple reflections and increased gas interaction, thereby enhancing attenuation and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light path is extended using multiple reflections in a compact enclosure, then the sensitivity and attenuation are improved, but the device complexity increases due to the need for multiple precisely configured reflective surfaces
Solution Approach 1:
The patent employs multiple curved reflective surfaces with specific eccentricities (e.g., first reflective surface with eccentricity 0.5-0.7, second with 0.3-0.5) to focus and redirect light waves through the gas sample multiple times. The curved geometry enables precise control of light paths without requiring complex mechanical adjustment mechanisms, thereby improving measurement precision while managing device complexity through geometric design
Solution Approach 2:
The patent integrates multiple reflective surfaces within a compact enclosure structure, nesting the optical components (light source, photodetector, and multiple reflective surfaces) within each other. This allows the light path to be extended through multiple reflections within a small footprint, achieving high sensitivity without proportionally increasing the overall device size or complexity
2Area of stationary object
If the enclosure size is reduced to maintain compactness, then the footprint is minimized, but the light wave attenuation and sensitivity are reduced
Solution Approach 1:
The patent extends the light path from a single linear dimension into multiple dimensional reflections within the enclosure. By using curved reflective surfaces to create multiple bounce paths, the effective light travel distance through the gas is increased in three-dimensional space while maintaining a compact two-dimensional footprint, thereby preserving sensitivity without increasing device area
Solution Approach 2:
The curved reflective surfaces with optimized eccentricities focus light waves to traverse the gas sample multiple times along curved paths. This geometric configuration maximizes the effective path length within the compact enclosure volume, enabling high attenuation and sensitivity while maintaining a small sensor footprint
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 design improves the attenuation of light waves, leading to more precise gas concentration estimation and increased sensitivity, while maintaining a compact footprint, thus enhancing the accuracy of gas analysis.
Implementation Method 1
the species composing a gas have absorption spectral properties different from each other. Thus, knowing a spectral absorption band of a gas species, its concentration can be determined by an estimation of the absorption of light passing through the gas
Implementation Method 2
its concentration can be determined by an estimation of the absorption of light passing through the gas, using Beer Lambert's law
Implementation Method 3
the light wave emitted by the light source is successively reflected by the reflecting surfaces, according to their respective rank, before converging towards the second focus of the last reflecting surface
Implementation Method 4
a measuring photodetector capable of detecting the light wave having passed through the enclosure
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
The invention relates to a gas sensor (1) comprising an enclosure (10) capable of receiving the gas (2), the sensor also comprising: a light source (11), configured to emit a light wave (11') which propagates in the enclosure (10) by forming a transmission cone (Ω1), referred to as first cone; a measurement photodetector (12) which is capable of detecting the light wave emitted by the light source (11) and has passed through the enclosure; the sensor being such that the enclosure (10) extends between two transverse walls (21, 22) arranged one opposite the other, the transverse walls being connected to one another by a peripheral wall (30) extending between the transverse walls, the peripheral wall (30) comprising: a first reflecting surface (SI), of rank 1, curved, with an eccentricity of less than 0.7, and having a first focus (Pl-1) and a second focus (Pl-2), the first reflecting surface being arranged opposite the light source (11); at least one reflecting surface (Sn) of rank n, curved, n being an integer strictly greater than 1, each surface of rank n having: a first focus (Pl-n), coinciding with the second focus of a reflecting surface of previous rank n-1; a second focus (P2-n), distinct from the first focus (Pl-n), coinciding with the first focus of a surface of following rank n+1; a last reflecting surface (SN), of rank N, curved, comprising a first focus (Pl-N), coinciding with the second focus of a reflecting surface of preceding rank N-1, the last reflecting surface also comprising a second focus (P2-N); in such a way that the light wave (11') emitted by the light source (11) is successively reflected by the reflecting surfaces before converging towards the second focus of the last reflecting surface.