乙烯(C2H4)是石油化工产业中的基本化工原料，具有爆炸性，也常被作为煤层自燃的标识性气体。为实现对低浓度乙烯的检测，搭建了基于近红外可调谐二极管激光器的低成本光声光谱测量系统。通过对乙烯近红外波段吸收谱线的分析，选择了乙烯位于1620.44 nm处的吸收谱线作为测量对象，并结合波长调制吸收技术，使用光声池的共振频率作为激光器的调制频率，利用吸收谱线的二次谐波信号实现了对乙烯浓度的反演。实验结果表明系统对于乙烯的测量准确度为0.688%，探测极限达到了1.16×10-5，对同一样品在30 min之内的连续测量验证了系统良好的稳定性，所有实验结果均显示了该套系统在乙烯痕量探测方面的应用价值。

Ethylene (C2H4) is a common chemical material in the petroleum and chemical industry. It is explosive and often used as identifier for coal spontaneous combustion. An inexpensive photoacoustic spectrometry based on near infrared tunable diode laser is developed to detect the ethylene with low concentration. By analyzing the near-infrared absorption line of ethylene, we choose absorption line of ethylene at 1620.44 nm as measuring object. By combining wavelength modulation absorption technique, resonant frequency of photoacoustic cell is used as modulation frequency, and the second harmonic signal of absorption line is used to realize inversion of ethylene gas concentration. The results show that the measurement accuracy of ethylene by the system is 0.688%. The detection limit of the system is up to be about 1.16×10-5. A continuous measurement for a gas sample in half an hour shows the stability of the system. All the results represent the application value of the system for trace detection of ethylene.