Absorption Spectrometer Synchronization via Optical Modulation

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Solution Overview

Problem

Existing absorption spectrometers for in-situ gas component measurement require significant equipment and assembly effort due to the need for complex coupling lines between light sources and detectors in industrial environments, particularly under conditions with aerosols.

Innovation Solution

An absorption spectrometer with a wavelength-tunable light source that sinusoidally modulates light with a high frequency and small amplitude, and a phase-sensitive demodulation system synchronized via a large amplitude sinusoidal modulation before the measurement period, allowing for reliable synchronization and reduced assembly complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coupling lines are provided and laid between light source and detector in industrial environments, then synchronization between transmitter and receiver can be achieved, but equipment and assembly effort increases significantly

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidequipment and assembly effort

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the synchronization function from the physical coupling line and implements it through optical modulation. The modulation device modulates the light signal itself to carry synchronization information, eliminating the need for separate coupling lines while maintaining reliable synchronization between transmitter and receiver.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electrical coupling line system with an optical modulation system. Instead of using physical wires to transmit synchronization signals, the system uses modulated light signals to carry synchronization information, thereby eliminating the complex coupling line infrastructure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If large amplitude sinusoidal modulation is used for synchronization, then signal-to-noise ratio improves for reliable synchronization, but measurement precision may be compromised during actual measurement

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidgas component concentration measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses periodic modulation with different amplitudes at different times. During the synchronization phase, large amplitude modulation is applied to ensure reliable signal detection. During the measurement phase, small amplitude modulation is used to maintain measurement precision. This time-varying periodic action resolves the contradiction between synchronization reliability and measurement precision.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent performs synchronization using large amplitude modulation in a time interval before the actual measurement begins. This preliminary synchronization action ensures that the receiver is properly synchronized before measurement starts, allowing the subsequent measurement phase to use small amplitude modulation for high precision without compromising synchronization reliability.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces the equipment and assembly effort while ensuring a high signal-to-noise ratio for accurate gas component concentration measurement even under poor transmission conditions, such as with aerosols, by using sinusoidal modulation for synchronization and phase-sensitive demodulation for precise measurement.

Implementation Method 1

measuring the concentration of a gas component in a measured gas based on wavelength modulation spectroscopy (WMS)... periodically varies the wavelength of the light of the tunable light source over an absorption line of interest of the gas component

Methodology Applied

Scientific EffectWavelength modulation spectroscopy: Absorption Spectroscopy

Implementation Method 2

a detector that detects the intensity of the light after passing through the measured gas

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 3

an evaluating device which contains means for phase-sensitive demodulation of a measurement signal generated by the detector at the frequency and/or one of its harmonics

Methodology Applied

Scientific EffectPhase-sensitive demodulation: Homodyne Detection

Data Source

PatentUS10132747B2Absorption spectrometer

Publication Date: 2018.11.20 SIEMENS AG

AI summary

An absorption spectrometer which measures a gas component concentration in a measured gas and which operates via wavelength modulation spectroscopy, wherein the light wavelength of a wavelength-tunable light source is periodically varied over a gas component absorption line of interest and simultaneously sinusoidally modulated with a high frequency and a low amplitude signal, and wherein the measurement signal of a detector is demodulated in a phase-sensitive manner at the frequency and/or a harmonic of the frequency and further analyzed, where modulation starts in each period or each n-th period with the frequency in a time interval before the beginning of the time function and is performed with a higher amplitude than during the time function to demodulate the measurement signal in a phase-synchronous manner, where a device provided for the phase-sensitive demodulation is synchronized during the time interval such that a cable for transmitting synchronization signals is no longer necessary.