基于LED光源的一氧化碳气体检测仪的设计

Research and Design on Infrared Detector for Carbon Monoxide

文章描绘并分析了一氧化碳分子的红外吸收光谱,推导了一氧化碳分子的吸收线型,估算了分子吸收系数,给出了气室设计的最佳长度。通过光谱分析发现,一氧化碳基频吸收比倍频吸收强约两个数量级,因此基频对应的4.60μm吸收谱带更适合于高灵敏度的一氧化碳气体检测。文中设计了一种基于LED光源的红外一氧化碳检测仪,结果表明,利用单LED光源、双探测器及反射式气室结构能够有效抑制环境变化、LED功率波动及探测器漂移等产生的噪声的干扰,进而具有较低的探测灵敏度,探测限为100×10-6。

The paper presents the intensities of carbon monoxide fundamental absorption bands, near infrared octave frequency band. It was found that the absorption strengths of fundamental bands are two orders of magnitude higher than those of octave frequency band theoretically, mid-infrared detection system is much better. A LED in the 4.60 μm region has been utilized as a light source for differential absorption measurement in the sensing of carbon monoxide. The output beams from the cells are focused on the signal and reference photodiodes of the dual-beam detector, respectively. One of the photodiodes is used for sensing carbon monoxide （sensing photodiodes） while the other is used for wavelength calibration （reference photodiodes）. Our system exhibits low detection limitation （100× 10^-6） and fast response time （13 s）, and has potential application in CO detectors.