太赫兹时域光谱反射式层析成像技术

改性聚丙烯（PP）材料由于其阻燃、高抗冲性能等特点被广泛应用在汽车仪表板、保险杠等汽车配件中，采用无损探伤技术对改性PP材料进行检测是汽车配件质量保证的必要手段。搭建了透射式太赫兹时域光谱系统及反射式太赫兹时域光谱成像系统，采用透射式THz-TDS系统对改性PP材料的光学参数进行了检测，测定了该材料在太赫兹波段的折射率，其数值为1.53。设计了一种改性PP材料平底洞样品，采用反射式THz-TDS成像系统对其进行成像，采用了反卷积滤波技术对THz信号进行处理，提高了信号的信噪比，提出了一种基于飞行时间的太赫兹时域光谱层析成像技术，采用已测定的改性PP材料的折射率，通过飞行时间层析成像技术对该样品的太赫兹检测结果进行了三维重构，厚度测量精度为0.01mm。

Terahertz time domain spectral reflective tomography technology

The modified polypropylene(PP) material has been widely used in dashboard, bumper and other auto parts because of its characteristics of flame retardant, high impact resistance, etc. It is a necessary means to improve the quality of auto parts by using the nondestructive testing technology to detect the modified PP material. A transmission terahertz time-domain spectroscopy(THz-TDS) imaging system and a reflective THz-TDS imaging system were built. The optical parameters of modified PP materials were extracted by adopting the transmission THz-TDS system. The refractive index, one of the optical parameters in terahertz band can be solved through the mathematics model, its value was 1.53. A kind of modified PP material sample with flat bottom holes was designed. The reflective THz-TDS imaging system was adopted for measuring the sample, the deconvolution method was used to filter the time domain THz signal, which largely improved the signal-to-noise ratio. What's more, THz-TDS tomography imaging technology was proposed based on the time of flight. Combined with the measured refractive index, the 3D structure of the modified PP material was reconstructed with the time of flight tomography imaging technique, the thickness accuracy is 0.01 mm.