Photoacoustic cell with adjustable resonant frequency and adjusting method

Abstract

The invention discloses a photoacoustic cell with adjustable resonant frequency and an adjusting method, and belongs to the technical field of gas detection. The photoacoustic cell provided by the invention is arranged in a thermostat and comprises a first buffer chamber, a second buffer chamber, a resonant cavity, a first light window, a second light window, a first movable structure and a secondmovable structure, wherein the first light window and the second light window are located on the outer side of the first buffer chamber and the outer side of the second buffer chamber respectively. According to the invention, the originally fixed buffer chamber and resonant cavity are improved into a movable structure with adjustable structural parameters by using piezoelectric ceramic; the adjusting capability of the resonant frequency and the reliability and the flexibility of the whole photoacoustic cell in a resonant working state are improved; moreover, the photoacoustic cell is arrangedin the constant-temperature box, so interference caused by external temperature and pressure change can be eliminated, the instability of resonant frequency in a resonant working process caused by external interference is avoided, the resonant frequency of the photoacoustic cell can be adjusted by changing the temperature, and the working stability and the signal-to-noise ratio of the detection system are improved.

Description

technical field [0001] The invention belongs to the technical field of gas detection, and more specifically relates to a photoacoustic cell with adjustable resonance frequency and an adjustment method. Background technique [0002] Photoacoustic spectroscopy is a spectroscopic technique based on the photoacoustic effect. In the photoacoustic effect, gas molecules absorb infrared light of a specific wavelength and are excited to a high-energy state. The molecules in the high-energy state convert the absorbed light energy into heat energy through a non-radiative transition and then return to a low-energy state. With frequency modulation, the thermal energy will show the same periodic change as the modulation frequency to generate sound waves. The sound signal is detected by the microphone and the final concentration of the gas is calculated. [0003] The core components that affect the sensitivity of the photoacoustic gas detection system mainly include light source, photoaco...

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Problems solved by technology

[0004] In view of the defects of the prior art, the object of the present invention is to provide a photoacoustic cell with adjustable resonant frequency and an adjustment method, which can adjust the working frequency to the standard resonant frequency, aiming to solve the problem of gas concentration caused by the drift of the resonant frequency of the photoacoustic cell. The problem of reduced detection ability

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