Study on a hybrid method about measuring the concentration of carbon monoxide gas based on 1.58m diode laser
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1.
Optical Engineering Research Institute, Southwest Jiaotong University, Chengdu 610031, China;
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2.
Modern Education Technology Center, Chengdu University, Chengdu 610106, China
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Received Date:
2010-03-10
Accepted Date:
2010-05-11
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Abstract
In order to measure the concentration of carbon monoxide gas in a smelting furnace in real time and with high precision, an 1.58m distributed feedback(DFB) laser was used to measure the absorption harmonics of different concentrations by means of laser frequency scanning. The hybrid algebra calculation of the maximum values of its first harmonic and second harmonics can effectively overcome the influence of laser aging, disperse and modulation change in the laser system on the measurement results. It is shown that the relative measurement error increases with the modulation linearly in the small-signal modulation and exponentially in the large-signal modulation. With the increase of transfer factor of laser driver current and laser frequency, the relative error will increase. The conclusion show that the CO gas concentration can be calculated efficiently, fast, in real-time and with high-precision by means of the hybrid calculation method of absorption lines at special frequencies of the first harmonic and second harmonic intensity.
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