一种纵向共振光声池谐振频率测量方法

Measurement method of resonance frequency for longitudinal resonant photoacoustic cells

为了快速准确测量共振光声池的谐振频率,采用基于共振声谱的光声池谐振频率测量法,搭建了光声光谱检测系统和共振声谱检测系统。对影响测量准确性的因素进行了实验分析。在不同气体体积分数的情况下,分别采用共振声谱法和光声信号强度标定法测量光声池的谐振频率。结果表明,共振声谱法测量的光声池共振频率与声信号激励电压、声源传播距离及角度无关;在5种不同体积分数的乙炔气体条件下,所测得的光声池谐振频率与通过光声信号强度法的结果最大偏差为1.1Hz,可认为两种方法测量结果具有一致性。该方法简单快速、可靠和准确,可用于确定光声池谐振频率。

Resonant frequency of a photoacoustic cell is one of its key parameters. In order to measure resonant frequency of a resonant photoacoustic cell quickly and accurately, a resonant frequency measurement method based on resonant acoustic spectroscopy was used to built a photoacoustic spectroscopy detection system and a resonant acoustic spectroscopy measurement system. The factors affecting the accuracy of measurement results were analyzed. Resonant frequency of the resonant photoacoustic cell was measured by the resonant acoustic spectroscopy method and photoacoustic signal intensity method respectively in the case of different gas concentrations. The experimental results indicate that the resonance frequency measured by the resonant acoustic spectroscopy method is independent of excitation voltage of the sound signal, distance and angle of sound source. Under the conditions of 5 different concentrations of acetylene(C2H2) gas, the maximum deviation of the resonant frequency between the resonance acoustic spectroscopy and photoacoustic signal intensity method is 1.1Hz. It is considered that the measured results of both the methods are consistent. The resonant acoustic spectroscopy method is simple, fast, reliable and accurate. It can be used to determine the resonant frequency of a photoacoustic cell.