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Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Flexible lock-in detection system based on synchronized computer plug-in boards applied in sensitive gas spectroscopy
Mats Andersson1, Linda Persson, Tomas Svensson
1Atomic Physics Division, Lund University, POBox 118, S-221 00 Lund, Sweden.
The Review of Scientific Instruments
|December 7, 2007
Summary
A new digital lock-in detection system enables high-resolution tunable diode laser spectroscopy. This flexible, compact system achieves high sensitivity for gas analysis in various materials.
Area of Science:
- Spectroscopy
- Laser Technology
- Digital Signal Processing
Background:
- Tunable diode laser spectroscopy requires sensitive detection methods.
- Existing lock-in detection systems can be complex and inflexible.
- Coherent sampling offers potential for improved signal processing.
Purpose of the Study:
- To develop a flexible and compact digital lock-in detection system.
- To apply this system for high-resolution tunable diode laser spectroscopy.
- To demonstrate its capability in analyzing gases in diverse samples.
Main Methods:
- Utilized coherent sampling with synchronized data acquisition cards on a single computer.
- Employed a software-controlled arbitrary waveform generator for laser modulation.
- Recorded detector signals using a four-channel analog/digital board for wavelength modulation spectroscopy.
Main Results:
- Achieved a detection sensitivity on the order of 10(-5), limited by interference fringes.
- Successfully measured multiple harmonics (1f, 2f, 3f, 4f) of the modulation signal.
- Demonstrated system's capability by analyzing molecular oxygen in ambient air and dispersed gases in plants and human tissue.
Conclusions:
- The developed digital lock-in detection system is effective for high-resolution spectroscopy.
- The system's flexibility and compactness make it suitable for various applications.
- Further improvements could mitigate interference fringe limitations for enhanced sensitivity.
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