Li Jingsong, Parchatka Uwe, Königstedt Rainer, Fischer Horst
Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany.
Opt Express. 2012 Mar 26;20(7):7590-601. doi: 10.1364/OE.20.007590.
A compact, mobile mid-infrared laser spectrometer based on a thermoelectrically (TE) cooled continuous-wave room temperature quantum cascade laser and TE-cooled detectors has been newly developed to demonstrate the applicability of high sensitivity and high precision measurements of atmospheric CO. Performance of the instrument was examined with periodic measurements of reference sample and ambient air at 1 Hz sampling rate and a 1-hourly calibration cycle. The typical precision evaluated from replicate measurements of reference sample over the course of 66-h is 1.41 ppbv. With the utilization of wavelet filtering to improve the spectral SNR and minimize the dispersion of concentration values, a better precision of 0.88 ppbv and a lower detection limit of ~0.4 ppbv with sub-second averaging time have been achieved without reducing the fast temporal response. Allan variance analysis indicates a CO measurement precision of ~0.28 ppbv for optimal integration time of approximate 50 s. The absolute accuracy is limited by the calibration gas standard. This completely thermoelectrically cooled system shows the capability of long-term, unattended and continuous operation at room temperature without complicated cryogenic cooling.
一种基于热电（TE）冷却的连续波室温量子级联激光器和TE冷却探测器的紧凑型移动中红外激光光谱仪已被新开发出来，以证明其在大气一氧化碳高灵敏度和高精度测量方面的适用性。该仪器的性能通过以1 Hz采样率和每小时一次的校准周期对参考样品和环境空气进行定期测量来检验。在66小时的过程中，对参考样品进行重复测量所评估的典型精度为1.41 ppbv。通过利用小波滤波来提高光谱信噪比并最小化浓度值的离散度，在不降低快速时间响应的情况下，实现了更好的精度0.88 ppbv和更低的检测限~0.4 ppbv（亚秒平均时间）。阿伦方差分析表明，对于约50秒的最佳积分时间，一氧化碳测量精度约为0.28 ppbv。绝对精度受校准气体标准的限制。这个完全热电冷却的系统显示出在室温下长期、无人值守和连续运行的能力，无需复杂的低温冷却。
