A photoacoustic cell with adjustable resonant frequency and its adjustment method

Abstract

The invention discloses a photoacoustic cell with adjustable resonance frequency and an adjustment method, belonging to the technical field of gas detection. The photoacoustic cell provided by the present invention is placed inside a constant temperature box, including 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 second movable structure; A light window and the second light window are respectively located outside the first buffer chamber and the second buffer chamber. The present invention uses piezoelectric ceramics to improve the original fixed buffer chamber and resonant cavity into a movable structure with adjustable structural parameters, which improves the ability to adjust the resonant frequency and the reliability and flexibility of the entire photoacoustic cell in a resonant working state, and , placing the photoacoustic cell in a constant temperature box can not only eliminate the interference caused by changes in external temperature and pressure, but also avoid the instability of the resonant frequency in the resonant working process caused by external interference, and adjust the photoacoustic cell by changing the temperature The resonant frequency of the pool can improve the working stability and signal-to-noise ratio of the detection system.

Description

technical field [0001] The invention belongs to the technical field of gas detection, and more specifically relates to a device and a method for solving the resonance frequency drift of a resonant photoacoustic cell. 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 s...

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Problems solved by technology

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a device and method for solving the drift of the resonant frequency of the resonant photoacoustic cell, which can adjust the working frequency to the standard resonant frequency, aiming to solve the problem caused by the drift of the resonant frequency of the photoacoustic cell. The problem of the decrease of gas concentration detection ability

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