反射式THz‒TDS用于轨道交通典型液体安检的实验

太赫兹时域光谱(THz-TDS)技术用于轨道交通易燃易爆危险液体的安全检测，需要兼顾速度和准确率。一般在大流量人群中，因为检测速度限制，不适合直接采用实验室常用的测试指纹谱之后再与样品数据库的吸收峰位置比对的方法来精确确定样品成分信息。针对轨道交通中典型液体样品，在常温常压和正常大气湿度(25 ℃、60%空气湿度)条件下，测试反射式THz-TDS的脉冲回波数据。建立非易燃易爆危险品、易燃易爆类、强酸类等分类数据库，结合样品光谱数据库特征，归纳了4种典型的时域脉冲谱线，即含有显著次级反射峰、微小次级反射峰、无反射峰和向下反转的次反射峰。依据太赫兹时域谱线次级反射峰的特征，结合分类识别决策模型，快速实现了综合分类判别，准确率达80%以上。

Reflective Terahertz Time-Domain Spectroscopy for security inspection of typical liquids in railway transportation

Speed and accuracy must both be taken into consideration when using Terahertz Time-Domain Spectroscopy(THz-TDS) for security inspection of flammable and explosive contraband liquids in railway transportation. Due to speed limitation, the exact comparison of the precise fingerprint location between testing results and database, which is the common method adopted in laboratory analysis, cannot be directly utilized for the security inspection of large passenger flow. The reflective terahertz time-domain spectroscopy data for typical liquids in railway transportation is acquired under standard temperature, pressure, and normal humidity level(25 ℃, RH 60%). The categorized time-domain database for non-flammable and non-explosive liquids, flammable and explosive liquids, and strong acid, is established. Based on the database, the typical time-domain pulse patterns can be classified into four categories, namely terahertz time domain spectroscopy with obvious secondary pulse, minor secondary pulse, no secondary pulse and obvious negative secondary pulse. According to terahertz time domain characteristics, rapid detection with better than 80% of accuracy is achieved through classification decision model.