LI Jun, JI Xin-ming, ZHOU Jia, et al. High sensitivity miniature infrared photo-acoustic gas sensing system[J]. 2011, 30(2): 84-87. DOI: 10.13873/j.1000-97872011.02.042.
A prototype of a highly sensitive miniaturized infrared photo-acoustic(PA)system is developed.The system can detect the volume fraction of ethylene gas below 20×10-9.Relationship between the PA signals and the testing phase is focused on
the reason of the phase change in testing is analyzed.A conclusion is obtained that under a fixed phase delay using lock-in amplifier to detect PA signals can get a high sensitivity.According to the research on the PA signal and phase delay.A design of miniature on PA cell is proposed.