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A Dual-Laser Sensor Based on Off-Axis Integrated Cavity Output Spectroscopy and Time-Division Multiplexing Method.
Kunyang Wang1,2, Ligang Shao1, Jiajin Chen1
1Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Anhui 230031, China.
Sensors (Basel, Switzerland)
|November 4, 2020
Summary
A new dual-laser sensor simultaneously measures CO2 and CH4 concentrations using integrated-cavity output spectroscopy. This compact sensor achieves high sensitivity and stability for real-time ambient air monitoring.
Area of Science:
- Spectroscopy
- Optical sensing
- Environmental monitoring
Background:
- Development of a compact dual-laser sensor utilizing off-axis integrated-cavity output spectroscopy (OA-ICOS) and time-division multiplexing.
- Integration of a dual-channel optical structure on a single optical cavity for simultaneous gas measurements.
Discussion:
- Experimental evaluation using standard air demonstrates the sensor's capability for simultaneous CO2 and CH4 detection.
- Achieved limits of detection (LoD) of 0.271 ppm for CO2 and 1.743 ppb for CH4 at 20s integration time.
- Noise equivalent absorption sensitivities of 2.68 × 10⁻¹⁰ cm⁻¹ Hz⁻¹/² for CO2 and 3.88 × 10⁻¹⁰ cm⁻¹ Hz⁻¹/² for CH4.
Key Insights:
- The dual-laser sensor exhibits excellent long-term stability, verified over 120 hours of continuous ambient air monitoring alongside a commercial instrument.
- Implementation of a first-order exponential moving average algorithm effectively filters data for accurate gas concentration estimation.
- The sensor's compact design and high performance make it suitable for various environmental and industrial applications.
Outlook:
- Potential for further miniaturization and integration into portable monitoring systems.
- Exploration of advanced signal processing techniques to enhance detection limits and reduce measurement times.
- Application in diverse fields requiring precise and simultaneous monitoring of CO2 and CH4, such as greenhouse gas tracking and industrial process control.
