In this paper, we propose a gas analyzer that uses a quantum cascade laser (QCL) and achieves high sensitivity and gas selectivity with simple configuration and signal processing. Feature quantities are extracted from an absorption-modulated signal, which is obtained by the logarithmic conversion of a detector signal receiving a wavelength-modulated laser light. The extracted feature quantities are used for the determination of target and interfering gas concentration with simple simultaneous linear equations. As a result of the demonstration of CO gas measurement with a gas analyzer consisting of a 4.6 μm pulsed QCL, a small-volume Herriott cell with a path length of 5 m and a thermopile as a photodetector, it is shown that the limit of detection is 2.0 ppb at the integration time of 1 s and that interference by N₂O can be eliminated. It is also shown that various disturbances such as spectral shift due to laser wavelength drift and spectral broadening due to partial pressure change of coexisting gases can be corrected by extracting appropriate additional feature quantities.

在本文中，我们提出了一种使用量子级联激光器（QCL）并通过简单的配置和信号处理即可实现高灵敏度和气体选择性的气体分析仪。从吸收调制信号中提取特征量，该吸收调制信号是通过对接收波长调制激光的检测器信号进行对数转换而获得的。提取的特征量通过简单的联立线性方程式用于确定目标气体和干扰气体浓度。通过气体分析仪对CO气体进行测量的结果，该气体分析仪由4.6μm脉冲QCL，路径长度为5 m的小体积Herriott池和热电堆作为光电探测器组成，表明检测极限在1 s的积分时间内为2.0 ppb，并且受到N _2的干扰O可以消除。还表明，可以通过提取适当的附加特征量来校正各种干扰，例如由于激光波长漂移引起的光谱偏移和由于共存气体的局部压力变化引起的光谱展宽。