Abstract：A trace-gas concentration system is designed based on photoacoustic spectroscopy. Erbium-doped fiber laser is used as a light source for acetylene detection. A T-type length-regulated photoacoustic cell is designed as first longitudinal single reflection resonance mode. The modulation frequency is 1099 Hz.Second-harmonic detection technology is used as the basic principle of the signal processing.Triangular wave is used to modulate the light source signal.The ratio between the second harmonic coefficients and the first harmonic coefficients as the system output, and the relationship curve about impact factors has been drawn. Experimental results with different concentrations of acetylene gas show that, the detection sensitivity of the system is 9.634×10－6,and signal-to-noise ratio is 41.52 dB.
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2013, Vol. 34 
