皮革检测鉴定的市场需求缺口巨大, 不同种类皮革, 尤其是不同种类真皮革无损、 无标记检测具有重要的应用价值。 利用太赫兹时域光谱技术系统地测试了不同种类真皮革和人工革的太赫兹透射光谱, 计算了不同真皮革和人工革的太赫兹吸收系数和折射率。 在0.2~1.5 THz范围内, 不同种类皮革的太赫兹吸收系数和折射率数值大小具有明显差异, 真皮革大于人工革; 且真皮革中, 爬行类皮革>鱼类皮革>哺乳类皮革。 进一步地, 猪、 牛、 羊真皮革在25~80 ℃加热过程中太赫兹时域光谱振幅变化均在60 ℃左右出现拐点, 而人工革无拐点; 且猪、 牛、 羊真皮革变化趋势各异。 为了验证皮革太赫兹光谱产生差异的原因, 首先对代表性皮革牛皮革、 人造革和合成革的主要组成成分牛皮胶原蛋白、 聚氯乙烯（PVC）和聚氨酯（PU）进行了太赫兹光谱测试, 牛皮胶原蛋白的太赫兹吸收系数和折射率大于聚氯乙烯和聚氨酯; 并且在25~80 ℃加热过程中胶原蛋白出现变化拐点, 而聚氯乙烯无。 实验结果显示, 皮革主要组成成分的太赫兹光谱特征的数值差异和变化趋势与对应皮革相同, 表明不同种类皮革间差异性的太赫兹光谱特征主要来源于其组成成分的不同。 基于此, 太赫兹光谱技术有望用于皮革的快速、 准确、 无损、 无标记检测, 用于区分不同种类真皮革和人工革, 尤其是分辨来源于爬行动物、 哺乳动物和鱼类的真皮革。

A huge demand and supply gap existed in the market about leather identification. The nondestructive detection method of different kinds of leather, especially different kinds of natural leather, has important application value. The terahertz (THz) transmission spectra of different kinds of natural leather and artificial leather have been systematically investigated and compared by THz time-domain spectroscopy (THz-TDS). In the range of 0.2 to 1.5 THz, the THz absorption coefficient and refractive index of natural leather are generally greater than those of artificial leather, and those of reptile leather, fish leather and mammal leather gradually decreased. There existed a turning point at about 60 ℃ in the amplitude change of THz time-domain spectroscopic curve during the heating process of natural leather from 25 to 80 ℃ with different variation tendency to pigskin, cowhide and sheepskin respectively, while it is absent to artificial leather. Further, the THz spectrum feathers of major components of leather, collagen, Polyvinyl chloride (PVC) and Polyurethane (PU) have been characterized to verify the cause of the difference of leather THz spectrum. The THz absorption coefficient and refractive index of collagen are greater than those of PVC and PU. The inflection point appears to collagen, but not to PVC during the same heating process. The characteristics of the THz spectrum of the composition of leather, collagen, PVC and PU have the similar numerical trends and changes, which indicates that the difference of the THz spectrum between different kinds of leather is mainly due to the difference in its composition. The work illustrates that the THz-TDS could be used to label-free distinguish artificial leather from natural leather and differentiate varieties of natural leathers from reptiles, mammals and fish.