Reducing temperature sensitivity of gas measurement using chirped-modulated photoacoustic spectroscopy

Abstract

Resonance frequency drift caused by a change in temperature greatly limits the application of high- Q resonators with high temperature sensitivity in photoacoustic (PA) gas detection systems. In this work, a chirp-wavelength combined modulation method was designed by incorporating a real-time frequency scanning in wavelength-modulated PA spectroscopy to reduce the influence of temperature changes on measurement. Theoretical analysis shows that the chirp rate depends on the precision requirements and the cutoff frequency of the cascaded low-pass filter. Trace acetylene measurement experiment at varying temperature verified that the proposed method can significantly reduce the temperature sensitivity within a preset temperature range. Thus, this method can effectively reduce the temperature sensitivity of a high- Q resonator for improving the measurement accuracy and detection limit in trace gas detection.

Photoacoustic Spectroscopy-Based Breath Analysis for SIBO

“…Due to the frequency drift caused by high concentrations of CO 2 , − modulation frequency tracking and calibration are necessary. By changing the size of the modulation frequency every 5 s, the scanning frequency is adjusted to find the maximum point of the photoacoustic signal.…”