光声腔的性能是决定基于光声光谱学的微量气体检测系统灵敏度的重要因素之一，光声腔的设计是建立光声光谱气体检测系统的关键环节。基于光声光谱技术及声学理论设计了一种长度可调的一阶纵向反馈谐振式光声腔，通过实际测量的方法直接得到谐振频率，有效避免了重复计算过程和制造过程中产生的误差，使测量更便捷，提高了系统检测灵敏度。建立了光声光谱气体检测系统，实验分析了谐振腔长度、光声腔长度以及光源功率对光声信号的影响，并测得系统信噪比为39.5，检测灵敏度为2.78×10-6。

The performance of photoacoustic cell is one of the important factors which determine the trace gas detection system sensitivity based on photoacoustic spectroscopy (PAS). The photoacoustic cell design is a key part of PAS gas detection system. A first-order longitudinal length adjustable feedback resonant photoacoustic cell is designed based on PAS and acoustic theory. The resonance frequency is conveniently achieved by actual measurement, which effectively avoids the double counting process and the manufacturing error, makes the measurement easier and improves the sensitivity of detection system. The PAS trace gas detection system is built. The impacts of cavity length, photoacoustic cell length and source power on photoacoustic signal are discussed experimentally. The signal to noise ratio is 39.5 and sensitivity is 2.78×10-6.