A double-channel methane (CH₄) sensor was developed using a dual-pass multipass cell (DP-MPC) and a novel method that combines averaging dual-channel concentration signals with optimized detector gain configuration. This DP-MPC features two input/output coupling holes, resulting in absorption path lengths of approximately 95.8 m and 35.8 m, respectively. By optimizing the photodetector gain configuration and averaging the dual-channel concentration signals, the detection performance of the sensor was further enhanced. Allan deviation analysis indicated that after optimizing the detector gain, the measurement precision after dual-channel averaging reaches 21 ppb with an integration time of 1 s at a concentration of 2 ppm CH₄, which is approximately 1.4 times higher than the measurement precision of the long-path channel (31 ppb) and short-path channel (30 ppb). The time required to achieve a measurement precision of 21 ppb is 2.4 s for the long-path channel and 2.1 s for the short-path channel. The response speed of the dual-channel averaging is approximately 2 times that of any single channel. Meanwhile, the sensor demonstrated its stability and reliability through continuous outdoor atmospheric CH₄ measurements.

中文翻译：

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基于双通道 Herriott 单元的双通道传感器，用于高精度测量甲烷


使用双通道多通道单元 （DP-MPC） 和一种将平均双通道浓度信号与优化的探测器增益配置相结合的新方法开发了双通道甲烷 （CH₄） 传感器。该 DP-MPC 具有两个输入/输出耦合孔，吸收路径长度分别约为 95.8 m 和 35.8 m。通过优化光电探测器增益配置和对双通道浓度信号求平均值，进一步增强了传感器的探测性能。Allan 偏差分析表明，优化检测器增益后，在 2 ppm CH₄ 浓度下，双通道平均后的测量精度达到 21 ppb，积分时间为 1 s，大约是长路径通道 （31 ppb） 和短路径通道 （30 ppb） 测量精度的 1.4 倍。达到 21 ppb 测量精度所需的时间是长路径通道 2.4 s 和短路径通道 2.1 s。双通道平均的响应速度大约是任何单通道的 2 倍。同时，该传感器通过连续的室外大气 CH₄ 测量证明了其稳定性和可靠性。