当待测气体浓度较高时,腔内吸收损耗较大,限制了腔衰荡光谱检测技术的检测量程。针对这一问题,分析了采样阈值与气体浓度检测之间的相关性,模拟了阈值调节对检测精度的影响,建立了描述阈值与气体浓度的动态响应范围的模型,提出了通过调节阈值实现检测量程扩展的方法。在实验中,利用腔衰荡光谱检测装置对不同浓度的甲烷标准气体进行测量,测量结果与理论模拟结果一致。通过调节检测阈值,将量程扩展到1×10 -4(体积分数),动态响应范围为2.72×10 4,最大引用误差为0.78%。该方法解决了腔衰荡光谱技术中低检出限和大量程不能同时满足的问题,为阈值参数的设置提供了分析方法。

When the gas concentration to be measured is high, the absorption loss in the cavity is large, which limits the measurement range of cavity ring-down spectroscopy. To solve this problem, the correlation between sampling threshold and gas concentration detection is analyzed, the influence of threshold adjustment on measurement accuracy is simulated, a model describing the dynamic response ranges of threshold and gas concentration is established, and a method for detection range extension is proposed by adjusting threshold. In the experiment, the methane standard gases with different concentrations are measured by the measurement device based on cavity ring-down spectroscopy, and the measured results are consistent with the theoretical simulation results. By adjusting the measurement threshold, the range is extended to 1×10 -4 (volume fraction), the dynamic response range is 2.72×10 4, and the maximum quoted error is 0.78%. The proposed method solves the problem that low detection limit and large range cannot be met simultaneously in the technology based on cavity ring-down spectroscopy and provides an analytical method for the setting of threshold parameters.