Applying Diode Laser Wavelength Modulation Spectroscopy to Detect Oxygen Concentration

Oxygen is not only important which people rely on but also one type of important industrial gas. Considering that there are some disadvantages of traditional methods to measure the oxygen concentration, the tunable diode laser absorption spectroscopy is researched in this paper combined with the phase-lock amplify technique. This method combines the high power, good monochrome, wavelength tuned with the drive current or temperature of laser and the advantage of phase-lock amplifier to improve the signal and noise ratio and the measure precision. Based on designing the detect system, the quantitative relation between the oxygen absorption crosssection and temperature at 760.26 nm is deduced. Moreover the linear bias of the detect result is 1%, and there is no interference caused by the other components mixed in the measured gas. So it can be seen that this technology has many advantages and can meet the application of industry very well.