【作者】 逯美红；

【导师】 沈京玲；

【作者基本信息】 首都师范大学 ， 光学， 2006， 硕士

【摘要】 太赫兹(THz)辐射是频率范围为100GHz-10THz的电磁辐射，这一波段位于电子学与光学的交界处，具有携带信息量丰富、亚皮秒量级脉宽、高时空相干性、低光子能量等特性，在天文、生物、计算机、通信等科学领域有着巨大的应用价值。早期由于缺乏有效的产生和探测方法对太赫兹技术的研究非常有限，但在近20年中，随着超快激光技术的迅速发展，为太赫兹脉冲的产生提供了稳定、可靠的激发光源，使太赫兹辐射的产生机理、检测技术和应用技术的研究得到蓬勃发展。太赫兹成像技术作为太赫兹波科学与技术中最具应用前景的发展方向之一已经受到非常广泛的关注。与微波、X射线、核磁共振NMR(nuclear magnetic resonance)成像相比，太赫兹成像不仅能够获得物质的光谱信息也能获得其结构信息。此外，太赫兹光源自身的低能性以及很强的穿透性使得利用太赫兹波技术能实现物质成分的无损鉴定与识别，这是传统的化学分析方法以及红外与可见光光谱分析技术难以实现的。 基于以上原因，本文对以下几个方面进行了研究：1．利用太赫兹成像技术对玉米种子的鉴定和识别。利用太赫兹时域光谱技术进行测量，实验结果再次表明，玉米种子的DNA及胚样品没有明显的特征峰，无法实现“指纹谱”特征识别。所以，本文提出利用透射式太赫兹逐点扫描成像技术对其进行成像，再利用空间图样方法进行计算识别。结果表明，只要不同样品的吸收谱之间形状有所差别，就可利用该方法实现鉴定和识别。2．利用太赫兹成像技术对毒品的鉴定和检测。实验上，以氯胺酮为例，采用太赫兹时域光谱技术，在氮气与空气测量环境下，对其分别进行了光谱测量，获得其折射率及吸收谱。氮气环境下的实验结果表明，毒品在所测量太赫兹频段有明显的特征峰，利用“指纹谱”特征进行毒品检测是可行的；而在空气中测量结果显示其特征峰不明显或有些是不真实的。为了弥补在干燥环境中测量的这种局限性，同样对其进行太赫兹成像，再利用空间图样方法进行计算识别。同时，也开发一些针对本课题的数据处理方法和相应软件，并且给出了实验结果并进行了分析讨论。3．太赫兹技术对化学混合物的成分分析研究。利用太赫兹成像技术和时域光谱技术对两种毒品混合物的定性实验研究，另外对毒品混合物成分的含量确定也进行了基本尝试。结果初步证明，利用这两种方法实现化学混合物的定性及定量分析是可行的。但对于太赫兹成像技术在这方面的研究只是个初步尝试，有待通过进一步研究得到更加满意的结果。更多还原

【Abstract】 Terahertz (THz) waves are those with frequencies between 100 GHz to 10 THz. With the location of the spectrum between the electronic and photonic domains, THz waves contain rich information involved in molecular vibaration and rotation, and have sub-picosecond pulse width, low photon energy and high space-time coherence. These unique features are indeed tremendous and imply astonishing applications in warious areas of science such as astronomy, biology, communications and computers. During recent 20 years, rapid progress in ultrafast laser technology provides a steady and reliable optical source for the THz pulses generation, which greatly promoted the development covering THz generation, detection and application. THz imaging, one of the most promising techniques, has attracted more and more attention for material distinguishing and non-destructive inspection. Comparing with the microwave, X-ray and nuclear magnetic resonance imaging, THz imaging can gain spectroscopic information along with the structural information. In addition, the low photon energy and strong penetrability of THz source make the non-destructive inspection and identification feasible, which is not possible using conventional analytical method of chemistry, infrared spectrum and visible light spectrum.Based on the above reasons, researches in this paper are made as follows: First, the identification of maize seeds with THz imaging. The results obtained again with terahertz time-domain spectroscopy (THz -TDS) indicated that there have no obvious absorption peaks and it is not possible to identify using "characteristic fringerprint spectra" technique. Therefore, we demonstrated an advanced THz imaging technique for identification of maize seeds by introducing the component spatial pattern analysis in this paper. The results showed that the identification is realized successfully as long as the data of image and absorption spectral information of samples are known and no specific features of samples spectra were required. Second, the detection and identification of illicit drugs with THz imaging. As an explanation, the characteristic fingerprint spectra and refractive index of Ketamine were first measured with THz -TDS both in the ambient air and in the nitrogen. The results obtained in the nitrogen indicated that there have obvious absorption peaks and it is feasible to detect illicit drugs using "characteristic fingerprint spectra" technique, while the results obtained in the ambient air更多还原