Dual trace gas detection using a compact two-channel multipass cell with dense and line spot patterns.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Optical Engineering

Background:

• Accurate simultaneous detection of atmospheric methane (CH4) and carbon dioxide (CO2) is crucial for environmental monitoring and safety.
• Existing sensors may lack the required sensitivity, stability, or cost-effectiveness for widespread application.

Purpose of the Study:

• To design and develop a highly sensitive dual-gas sensor for simultaneous atmospheric CH4 and CO2 detection.
• To optimize the sensor's multipass cell (MPC) configuration for enhanced performance and accelerated design.

Main Methods:

• Utilized two distributed feedback lasers emitting at 1653 nm and 2004 nm for CH4 and CO2 detection, respectively.
• Employed a compact, two-channel multipass cell (MPC) with optical path lengths of 27.6 m and 2.1 m within a 233 cm³ volume.
• Applied the nondominated sorting genetic algorithm for intelligent optimization of the MPC configuration.

Main Results:

• Achieved optimal detection precisions of 4.4 ppb for CH4 (at 76 s integration) and 437.8 ppb for CO2 (at 271 s integration) based on Allan deviation analysis.
• Demonstrated the sensor's stability and robustness through simultaneous atmospheric measurements.
• The novel two-channel MPC design achieved long optical path lengths in a small volume.

Conclusions:

• The developed dual-gas sensor offers high sensitivity, stability, and cost-effectiveness.
• Its simple structure and superior performance make it suitable for various trace gas sensing applications.
• Potential applications include environmental monitoring, safety inspections, and clinical diagnosis.