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Proceedings Paper

Research on reduction of long-term distortions and suppression of light intensity fluctuations in a TDLAS system
Author(s): Guo-jie Tu; Yu Wang; Feng-zhong Dong
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Paper Abstract

For any tunable diode laser absorption spectroscopy (TDLAS) system, its performance is often degraded by long-term distortion and fluctuations of light intensity. The source of long-term distortion and the corresponding proposal are discussed at first in this paper. It is proved that the long-term distortion of the system is mainly induced by the change of wavelength dependent transfer function. A balanced optical path can be used to reduce it effectively. In order to decrease the disturbance of intensity fluctuation, a novel method for online correction is presented. It is developed according to the linear relation between the peaks of harmonic power spectra and the incident light intensity. It is demonstrated by the experiments and explained as residual sum frequency and difference frequency power of signal and reference after the lock-in amplifier. This method could achieve real-time light intensity correction with only little calculation. By using a 17.5m multi-pass cell, the experiments show that the system can achieve about 20ppmv stability for long-term continual monitoring. Allan variance indicates that the detection limit for short-term measurement is between 0.3ppmv and 1.5ppmv depending on the response time allowed by the instrument.

Paper Details

Date Published: 30 November 2011
PDF: 7 pages
Proc. SPIE 8201, 2011 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 82010H (30 November 2011); doi: 10.1117/12.910065
Show Author Affiliations
Guo-jie Tu, Anhui Institute of Optics and Fine Mechanics (China)
Yu Wang, Anhui Institute of Optics and Fine Mechanics (China)
Feng-zhong Dong, Anhui Institute of Optics and Fine Mechanics (China)


Published in SPIE Proceedings Vol. 8201:
2011 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems
Xinyong Dong; Xiaoyi Bao; Perry Ping Shum; Tiegen Liu, Editor(s)

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