Multi-Wavelength TDLAS Sensor for Compact Gas Detection
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Solution Overview
Problem
Current gas concentration measurement techniques, such as TDLAS, are limited in measuring multiple gases simultaneously due to the need for multiple laser sources and detectors, resulting in bulky and complex systems with reduced accuracy, and a lack of compact solutions for applications requiring precise, sensitive measurements.
Innovation Solution
A compact optical apparatus comprising a multi-wavelength laser module with closely arranged tunable diode laser sources and a multi-layered/multi-band detector, allowing for simultaneous measurement of multiple gas concentrations without additional optics, using overlapping beam paths and a single detector unit capable of detecting broader wavelength ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple laser sources and detectors are used to measure multiple gases simultaneously, then measurement capability for multiple gases is improved, but system complexity and size increase
Solution Approach 1:
The patent combines multiple laser sources and multiple detectors into a single integrated sensor unit. The laser sources are positioned in close proximity and share common optical paths, while the detectors are integrated onto a single semiconductor substrate. This merging approach enables simultaneous measurement of multiple gases while significantly reducing system complexity compared to traditional separate laser-detector systems.
Solution Approach 2:
The integrated sensor design allows a single device to perform multiple gas measurement functions simultaneously. The multi-layered detector structure with different semiconductor materials enables detection of multiple wavelength ranges, making the system universally applicable for measuring various gas compositions without requiring separate specialized devices for each gas type.
2Adaptability or versatility
If multiple laser sources and detectors are used with overlapped beams, then multiple gas measurement is enabled, but optical components and alignment requirements increase system complexity
Solution Approach 1:
The patent extracts and eliminates unnecessary optical components from the measurement system. By positioning laser sources in close proximity and utilizing the natural divergence and overlap of their beams in free space, the system removes the need for complex optical elements like beam combining optics, mirrors, and lenses that would otherwise be required to achieve beam overlap. This extraction of redundant components simplifies the optical path while maintaining multiple gas measurement capability.
3Adaptability or versatility
If additional optics are used to combine laser beams, then multiple wavelength detection is achieved, but measurement accuracy decreases due to optical noise
Solution Approach 1:
The patent removes additional optical components from the system that would introduce noise and reduce measurement accuracy. By allowing laser beams to overlap naturally in free space without using beam combining optics, mirrors, or dichroic mirrors, the system eliminates sources of optical noise, scattering, and absorption that would degrade measurement precision. The direct optical path from laser sources through the gas sample to the integrated detectors maintains high measurement accuracy.
4Volume of moving object
If a compact sensor design is implemented, then system size is reduced, but the ability to accommodate multiple lasers and detectors is limited
Solution Approach 1:
The patent implements a nested structure where multiple laser sources are positioned in close proximity within a compact housing, and multiple detector layers are integrated onto a single semiconductor substrate. The laser sources share common optical paths and the detectors are stacked in layers, allowing multiple functional elements to be nested within a small volume. This nested arrangement enables compact sensor design while maintaining the capability to measure multiple gas compositions simultaneously.
Solution Approach 2:
The patent transitions from a planar arrangement of optical components to a three-dimensional integrated structure. The multi-layered detector uses vertical stacking of semiconductor layers with different bandgaps to detect multiple wavelength ranges, utilizing the third dimension (depth) rather than spreading components out in a large planar area. This dimensional transition enables compact sizing while preserving multiple gas measurement functionality.
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
Enables precise, simultaneous measurement of multiple gas concentrations in a compact and sensitive manner, reducing system complexity and optical noise, while maintaining high measurement accuracy and sensitivity.
Implementation Method 1
One particularly powerful approach is to use a tunable diode laser and a technique commonly known as tunable diode laser absorption spectroscopy (TDLAS). In this technique laser light is emitted through the gas where the resulting gas absorption is registered by a detector
Implementation Method 2
A compact optical sensor is used for measuring multiple gas concentrations using multiple lasers sources with overlapped laser beams
Implementation Method 3
The detector is sensitive to much broader wavelengths than the laser source
Data Source
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AI summary
A compact apparatus for detecting multiple gases, e. g., in a closed container, is disclosed. The apparatus comprises a multi-wavelength laser module (4) and a multi-wavelength detector (1), the detector comprising a stack of at least two material layers (2, 3) arranged along the same optical axis, wherein each layer is designed to detect a specific wavelength range different from the wavelength ranges detected by the other layers. The laser module may comprise at least two laser sources (5, 6) configured to emit different wavelengths, said laser sources being positioned close to each other so as to enable overlapping laser beam paths (7). The laser sources may be tunable diode laser or may be made of different laser chips arranged in a same laser housing. The apparatus may be configured as a TDLAS apparatus.