Pulsed Light Source Gas Sensor Aging Reduction
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Solution Overview
Problem
Existing gas analysis devices using pulsed light sources suffer from rapid aging, which affects the accuracy of gas composition measurements, and require additional components like reference photodetectors for spectral analysis.
Innovation Solution
A method and sensor design that modify the activation signal for the light source to include an initial period at a high level, followed by a nominal period at a lower level, and optionally a final period with a sinusoidal decrease, to optimize the shape of light pulses and reduce the need for analog filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulsed light source is used for gas analysis, then the measurement capability is provided, but the light source undergoes rapid aging resulting in decreased pulse amplitude
Solution Approach 1:
The patent applies periodic pulsed action to the light source, but with optimized parameters. By using pulses with duration between 100 μs and 10 ms at a repetition frequency between 0.1 Hz and 100 Hz, the system achieves both measurement capability and reduced aging. The periodic illumination allows the light source to rest between pulses, reducing cumulative stress and thermal load, thereby extending lifetime while maintaining measurement functionality.
Solution Approach 2:
The patent implements a warm-up period before measurements and a stabilization period between pulses. The light source is pre-heated to operating temperature before actual measurements begin, and each pulse includes a rise time and fall time that allow gradual heating and cooling. This preliminary action prevents thermal shock and reduces stress on the light source, delaying aging while maintaining measurement accuracy.
2Measurement precision
If conventional pulsed light sources are used, then gas absorption measurement is enabled, but spectral analysis requires additional reference photodetectors and signal-shaping filters
Solution Approach 1:
The patent extracts and removes the need for reference photodetectors and analog signal-shaping filters from the system. By using a pulsed light source with specifically optimized parameters (pulse duration 100 μs to 10 ms, repetition frequency 0.1 Hz to 100 Hz), the system generates light pulses that naturally produce clear absorption signals without requiring additional reference detectors or complex analog filtering circuitry, thereby simplifying the device while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical/analog signal-shaping filter system with a digitally processed approach. Instead of using analog filters to shape the light pulse signal, the system uses digital signal processing on the photodetector output. The optimized pulse parameters ensure that the raw signal contains sufficient information for spectral analysis, eliminating the need for analog filter components and reducing device complexity.
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 proposed solution delays the aging of the light source, allows for more accurate gas composition measurements, and simplifies the spectral analysis process by optimizing the light pulse shape without the need for additional signal-shaping filters.
Implementation Method 1
the species from which the gas is composed have spectral absorption properties that are different from one another. Thus, if an absorption spectral band of a gaseous species is known, the concentration of the latter may be determined via an estimation of the absorption of the light passing through the gas
Implementation Method 2
the concentration of a gaseous species present in the gas to be estimated via an estimation of the absorption of the light passing through the gas, using the Beer-Lambert law
Implementation Method 3
spectral absorption properties that are different from one another. Thus, if an absorption spectral band of a gaseous species is known
Data Source
AI summary
A method for measuring an amount of a gaseous species present in a gas, the gaseous species absorbing light in an absorption spectral band, comprises placing the gas between a light source and a measuring photodetector. The light source is configured to emit a light wave that propagates through the gas to the measuring photodetector. The light source is activated so as to illuminate the gas, so that the light source emits a light pulse. The method also includes measuring, with the measuring photodetector, a measurement intensity of a light wave transmitted by the gas during the illumination, in a measurement spectral band. The measurement spectral band comprises the absorption spectral band. The light source is activated using a pulsed activation signal, each pulse having a specific form, notably to reduce aging of the source.