Remote Gas Detection Using Dual-Beam Laser System
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Solution Overview
Problem
Existing remote gas detection methods face inaccuracies in determining gas concentration due to uncertainties in distance measurement, especially in leak detection on gas-carrying objects, and are affected by background gas quantities.
Innovation Solution
A device and method that utilize a monomode excitation laser beam with wavelength modulation for gas detection, combined with a distance-measuring beam for precise distance determination via phase measurement or FMCW, allowing for accurate calculation of gas concentration by evaluating the attenuation of the excitation laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a separate device or estimation method is used for distance measurement, then the device complexity is reduced, but the measurement precision of gas concentration deteriorates due to inaccurate distance determination
Solution Approach 1:
The patent combines the gas detection function and distance measurement function into a single integrated device. The laser unit emits both the excitation laser beam for gas detection and the distance-measuring beam for distance determination. The control unit processes both types of measurements and coordinates their execution, merging what would traditionally be separate devices into one unified system.
Solution Approach 2:
The laser unit serves multiple functions: it generates the excitation laser beam for gas absorption detection and also generates the distance-measuring beam for spatial distance determination. The control unit performs both gas concentration calculation and distance measurement processing, making the device multi-functional and eliminating the need for separate estimation devices.
2Ease of operation
If the distance measurement is not precisely determined, then the ease of operation is improved, but the measurement precision of gas concentration deteriorates due to incorrect absorption depth determination
Solution Approach 1:
The control unit receives the detected distance-measuring beam signal, determines the spatial distance based on this signal, and uses this distance information to calculate the gas concentration. The system continuously adjusts and coordinates the excitation laser beam and distance-measuring beam based on real-time distance feedback, ensuring accurate correlation between measured distance and absorption depth.
3Device complexity
If the excitation laser beam and distance-measuring beam are emitted along different optical paths, then the device complexity is reduced, but the measurement precision deteriorates because the measured distance does not correspond to the absorption distance
Solution Approach 1:
The patent explicitly configures the illumination device to emit both the excitation laser beam and the distance-measuring beam along the same optical path. This ensures that the distance measured by the distance-measuring beam corresponds exactly to the absorption path length of the excitation laser beam through the gas, eliminating discrepancies between measured and actual absorption distances.
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 enables more accurate and sensitive measurement of gas concentration by ensuring the measured distance corresponds to the absorption distance, reducing errors and improving detection precision.
Implementation Method 1
Methods and devices are known in the art that utilize laser spectroscopy, particularly with wavelengths in the near and mid-infrared range. In these methods, a laser beam with a specific wavelength irradiates a volume containing the gas to be analyzed. Depending on the type of gas, the laser radiation excites various molecular vibrations and rotational transitions within the gas, resulting in different absorption characteristics depending on the gas.
Implementation Method 2
To detect the laser radiation that interacts with the gases, a reflection geometry is often used. This means the laser beam is reflected off a surface, such as the wall of a gas pipeline, back towards the point of emission and detected by a suitable detection device sensitive to the emitted wavelength of the laser beam.
Implementation Method 3
the evaluation device determines the spatial distance between the device and the object from the transmitted signal, wherein the spatial distance is determined by means of a phase measurement or an FMCW distance measurement
Data Source
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AI summary
The present invention relates to a device for remote detection of a target gas comprising an illumination device with which an excitation laser beam is emitted, a modulation device for modulating a wavelength of the excitation laser beam with a first frequency, a detection device for detecting the excitation laser beam after reflection and/or scattering at an object, and an evaluation device which receives from the detection device a signal representing the detected excitation laser beam, from which the evaluation device determines an average column density of the target gas based on the attenuation of the excitation laser beam.To provide a device and method for the remote detection of a target gas that enables a more accurate concentration measurement of the target gas, it is proposed according to the invention that the illumination device additionally emits a distance-measuring beam which travels along the same optical path as the excitation laser beam and whose amplitude or wavelength is modulated by the modulation device with a second frequency and which is also detected by the detection device, so that a signal representing the distance-measuring beam is transmitted to the evaluation device, from which the distance to the object is determined, so that the mean gas concentration of the target gas is determined from the mean column density and the spatial distance.