美洲山核桃是美国最重要的坚果之一, 内部虫害是影响山核桃质量的重要因素。 为了实现美洲山核桃内部虫害的有效快速、 无损检测, 初步探索应用太赫兹光谱技术检测山核桃虫害研究。 收集山核桃样本并制作核桃仁1, 2, 3 mm均匀厚度的切片, 切片大小为2 cm×1 cm, 按照同样的尺寸制作核桃壳和核桃仁中间夹层的切片; 利用太赫兹时域光谱设备采集不同切片0～2THz波段的太赫兹吸收光谱, 并对比分析了所测切片的光谱特性; 采集了活体烟草天蛾切片和干燥的山核桃虫害切片的太赫兹时域光谱, 由于活体害虫的较高含水量以及太赫兹光谱对水分等极性分子的强吸收特性, 与山核桃切片对比发现, 活体虫害呈现非常明显的光谱吸收特性; 最后, 对整个山核桃样本进行了无损透射试验。 研究表明, 太赫兹光谱技术在检测山核桃内部虫害方面具有较好的应用潜力, 为进一步认识太赫兹光谱性质, 掌握样品制备方法、 实验测试方法和数据获取及光学参数计算方法, 应用太赫兹光谱技术开展山核桃内部虫害快速无损检测提供参考。

Pecan is an important nut in US, however, the inner insect influences pecan’s quality a lot. To realize the nondestructive detection of insect damage in American pecans rapidly and efficiently, preliminary research on insect damage detection in pecans was conducted based on terahertz spectroscopy. Firstly, a set of native pecan nuts were collected and were manually sliced with a thickness of about 1, 2 and 3 mm and with a size of about 2 cm(length)×1 cm(width) for every pecan nutmeat; Pecan shell and inner separator were also cut into the same size. Secondly, the absorption spectra of the nutmeat slices, shell, and inner separator were collected using THz time-domain spectroscopy (THz-TDS) developed by a group of researchers at Oklahoma State University, and the spectral characteristic of the slices was analyzed. Thirdly, the absorption spectra of the alive manduca sexta and dry pecan weevil were collected, and due to the high contents in the insects, very obvious spectral characteristics were found. Finally, the transmission experiment was conducted with the whole pecans. The results from the preliminary study show a potential application of THz technology for insect damage detection. This research provides a reference for further understanding terahertz and exploring sample preparation methods, test methods, data acquisition and optical parameters calculation methods, and developing nondestructive detection system for insect damage in American pecans based on terahertz technology.