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Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
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A Width Measurement Method of Line Shape Based on Second Harmonic Peak and Modulation Amplitude
Shan Lin1,2, Jun Chang1, Jiachen Sun1
1School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Qingdao 266200, China.
Sensors (Basel, Switzerland)
|January 8, 2023
Summary
This study introduces a new method for measuring spectral line width in absorption spectroscopy. The technique, utilizing wavelength modulation spectroscopy, achieves high accuracy for gases like methane and carbon dioxide.
Area of Science:
- Spectroscopy
- Gas Sensing
- Laser Technology
Background:
- Spectral line width is crucial for absorption spectroscopy sensing.
- Wavelength modulation spectroscopy offers high sensitivity and low noise.
Purpose of the Study:
- To develop a novel and accurate method for measuring spectral line width.
- To simplify data acquisition in wavelength modulation spectroscopy.
Main Methods:
- Theoretical derivation of the relationship between line width, modulation amplitude, and second harmonic amplitude.
- Simulation of methane (CH4) and carbon dioxide (CO2) absorption lines.
- Experimental validation using a distributed feedback laser diode near 1653 nm.
Main Results:
- The novel method demonstrated a relative error of approximately 1% compared to theoretical data for CH4 and CO2.
- Experimental results validated the numerical simulations.
- The method simplifies data acquisition by requiring only the measurement of second harmonic peaks.
Conclusions:
- The proposed method accurately measures spectral line width using wavelength modulation spectroscopy.
- This technique enhances the practicality of absorption spectroscopy sensing by reducing data acquisition complexity.
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