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太赫兹时域光谱(THz-TDS)技术因具有动态范围大、灵敏度和信噪比高等优点在气体检测领域中日益受到重视,然而检测系统内水对太赫兹波的强烈吸收会对气体解调结果产生严重影响。在常温常压、检测系统内有水气存在的情况下利用THz-TDS技术对不同浓度的氨气进行定量检测,并提出一种比例法浓度解调方法降低了水气对氨气浓度解调的影响。为了验证提出算法的有效性,与直接差分法和湿度补偿法两种浓度解调方法进行了比较。结果表明,当氨气与太赫兹波的作用光程为96 mm时,利用比例法可以使气体检测灵敏度提高为33.0mg/m3,浓度反演误差控制在48.2mg/m3以内,相比直接差分法和湿度补偿法浓度反演误差降低达84.6%和77.4%。
Terahertz time-domain spectroscopy (THz-TDS) technology is gaining more and more attention in the field of gas detection due to its advantages of large dynamic range, high sensitivity and high signal-to-noise ratio. However, the strong absorption of terahertz waves by the water in the detection system will degrade the gas The result has serious implications. At room temperature and atmospheric pressure, the detection system exists in the presence of water gas using THz-TDS technology for quantitative detection of ammonia at different concentrations and proposed a proportional method of concentration of the demodulation method to reduce the ammonia gas concentration demodulation Impact. In order to verify the effectiveness of the proposed algorithm, compared with the direct difference method and the humidity compensation method of two kinds of concentration demodulation. The results show that when the optical path of ammonia and terahertz wave is 96 mm, the sensitivity of gas detection can be improved to 33.0 mg / m3 by proportional method and the error of concentration inversion can be controlled within 48.2 mg / m3. Compared with direct difference The error of inversion of concentration and humidity compensation method was reduced by 84.6% and 77.4% respectively.