Spectroscopy and Spectral Analysis, Volume. 32, Issue 4, 910(2012)
Study on Wavelength Locking Technology in Trace Gases Detection System Based on Laser Techniques
In the trace gases detection system with tunable diode laser absorption spectroscopy (TDLAS) technology, the measurement of trace gases concentration was influenced by the laser wavelength drift resulting from the change in ambient temperature and noise of laser control electronics. With open-path TDLAS ammonia concentration detection system as an example, in the present paper the scanning law of laser center wavelength with current was analyzed, and the adaptive locking method of scanning laser center wavelength was presented based on controlling laser current. The aligning algorithm of measurement spectroscopy with calibration reference spectroscopy was studied. The open-path ammonia concentration was achieved in real time. Experiment results show that the precision and the stability of retrieving the concentration of trace gases were improved satisfactorily by wavelength locking. The variation of ammonia concentration has an obvious diurnal periodicity, which increased in rush hour time and got to the maximum at noon, then decreased at night. The system detection limit is about 3.8 mg·m-3·m.
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WANG Li-ming, ZHANG Yu-jun, HE Ying, YOU Kun, LIU Jian-guo, LIU Wen-qing. Study on Wavelength Locking Technology in Trace Gases Detection System Based on Laser Techniques[J]. Spectroscopy and Spectral Analysis, 2012, 32(4): 910
Received: Jul. 27, 2011
Accepted: --
Published Online: Apr. 16, 2012
The Author Email: Li-ming WANG (wanglm@aiofm.ac.cn)