基于中红外可调谐二极管激光吸收光谱技术研究了实现高信噪比低浓度一氧化氮(NO)的测量方法;选取谱线强度较高的1926 cm ^-1附近的中红外NO吸收谱线,利用带间级联激光器(ICL),使用波长调制法在常温下对NO进行测量;通过改变ICL的调制参数,分析了调制电流在3~25 mA范围内变化时,体积分数为0.46×10 ^-4~1.31×10 ^-4的NO气体的测量结果及信噪比。结果表明:当设定调制电流为11 mA时,信噪比最佳;对体积分数为0.5×10 ^-5~2.0×10 ^-5的NO进行测量时,测量结果具有较高的信噪比。

Based on the mid-infrared tunable diode laser absorption spectroscopy, we study the measurement method of nitric oxide (NO) with low concentrations and high signal-to-noise ratios. A mid-infrared NO absorption line at about 1926 cm -1 with strong absorption line strength is selected, and the NO measurement at ambient temperature is conducted with wavelength modulation method using an interband cascade laser (ICL). By changing the modulation parameters of the ICL, we investigate measurement results and signal-to-noise ratios of NO with different volume fractions (0.46×10 -4-1.31×10 -4) at different modulation currents (3-25 mA). The results show that the signal-to-noise ratio is the best when the modulation current is 11 mA. The measurement results of NO with volume fractions from 0.5×10 -5 to 2.0×10 -5 have high signal-to-noise ratios.