Palm-Sized Laser Spectrometer with High Robustness and Sensitivity for Trace Gas Detection Using a Novel Double-Layer...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Environmental Monitoring

Background:

• Trace gas detection is crucial for environmental monitoring and industrial safety.
• Existing sensors often lack portability and sensitivity for real-time, in-situ measurements.

Purpose of the Study:

• To develop a palm-sized, highly sensitive laser spectrometer for trace gas detection.
• To demonstrate the sensor's capability for measuring methane (CH4) in ambient air.

Main Methods:

• Tunable diode laser absorption spectroscopy (TDLAS) combined with a novel double-layer toroidal absorption cell.
• Calibration-free scanned wavelength modulation spectroscopy (WMS) for gas concentration determination.
• Development of a compact, homemade electronic system for laser control, signal processing, and data acquisition.

Main Results:

• A miniaturized spectrometer (24 × 15 × 16 cm³) with an 8.35 m effective optical path length was created.
• Methane (CH4) in ambient air was successfully measured using a distributed feedback (DFB) laser at 1.653 μm.
• The sensor demonstrated high stability with low standard deviations (0.38 ppm for vibration, 0.11 ppm for temperature) and achieved a minimum detection limit of 22 ppb for CH4 with a 57.8 s integration time.
• Continuous 2-day atmospheric CH4 measurement validated the sensor's feasibility and robustness.

Conclusions:

• The developed palm-sized laser spectrometer offers a sensitive and robust solution for trace gas detection.
• Its compact design and high performance make it suitable for deployment on unmanned aerial vehicles (UAVs) or mobile robots for environmental monitoring.
• This technology represents a significant advancement in portable gas sensing capabilities.