【作者】 周燕；

【导师】 张存林；

【作者基本信息】 首都师范大学 ， 光学， 2007， 硕士

【摘要】 太赫兹(THz)可以如X射线、可见光等辐射一样，作为物体成像的光源，由于其独特的性质，使得THz成像技术在安全检查、航天航空领域等方面都有着巨大的应用潜力。单从THz波形式上，THz成像技术大致可以分为脉冲成像和连续波成像两类。基于很多生物和化学媒介物质在THz范围有着明显的特征，外加脉冲成像自身独特的成像优势，脉冲成像已经成为一种很多应用领域中的重要选择。但随着半导体技术的发展，小型、相对快速，且易操作的便携式连续波成像系统成为现实，在诸多应用领域日益显示其实用性，成为脉冲成像之外的另一种重要的选择，共同促使了THz成像技术蓬勃发展。本论文主要是围绕连续THz波成像技术展开，从理论和实验的角度分析此技术的一些关键问题，更多地论证连续THz成像技术的应用性，为今后深入的研究和探索提供了一定的借鉴。论文的主要工作有：(1)调试连续THz成像系统，讨论连续波成像原理，数据采集等问题，论证这一技术的易操作、小型、相对快速等特点。且由于数据采集卡和扫描器之间速度的不匹配，图像中出现错位问题，通过综合改变平移台线速度、加速度和位置延迟参量，减少错位现象，优化系统。(2)利用0.2THz连续波成像系统，检测隐蔽的金属刀片，手机和手机袋中手机的内部结构，隐藏的铅字，玻璃钢的烧蚀程度，航天泡沫面板中的人工缺陷，航天泡沫中的裂缝、空洞及脱粘缺陷，并结合样品在THz范围的特性，理论解释实验结果，从实验上论证连续THz波成像技术在安全检测，有素描底的艺术品研究，航天航空材料烧蚀程度检测和航天泡沫缺陷检测等方面的应用价值。发现了酒精可优化裂缝检测的结果，同时，研究了缺陷面积、缺陷深度和缺陷边界对泡沫缺陷检测结果的影响。(3)讨论0.2THz和0.38THz成像系统，对比系统的实验装置，且从理论和实验上比较了成像特性。0.38THz系统有更好的图像分辨率，0.2THz系统有更好的信噪比，图像质量高。对于如聚氨酯泡沫材料，0.38THz系统有更好的图像对比度，0.2THz系统有更好的穿透性，可检测的泡沫厚度相对大。同时，利用8种图像处理算法，对0.2THz和0.38THz系统所成的原图像进行处理，提取更多信息特征，更易识别出要检测的目标。最后，以玻璃钢原图像为例证明，优化后的图像结果更利于实验结果分析，避免了因为原图像不清晰而无法进行的结果鉴别，提高了连续波成像技术的应用能力。更多还原

【Abstract】 Terahertz (THz) can be used as imaging light source, just like X radiation and visible light. Because its’ special characteristics, THz imaging technology has huge application potentiality in biological medicine, security inspection, testing of aerospace materials aspects and so on. Solely depending on the type of THz, THz imaging technology can be divided into pulsed and continuous-wave (CW) THz imaging. Based on the distinguished characteristics of many biologic and chemical media in THz range, and special imaging advantages of pulsed imaging, pulsed imaging has become an important choice in many applied fields. But with the development of semiconductor technologies, a compact, relative fast, easily operated and portable CW imaging system has been realized, showing its’ practicability increasingly in many applied fields, and become another important choice apart from pulsed imaging, promoting development of THz imaging technologies together.This thesis mainly focuses on the CW THz imaging technology, analyzing a few critical questions from theoretical and experiment aspects, more concerned with the applications of CW THz imaging technology, which are very essential to further research and exploration. The main research works are listed as follows:(1) Debug the CW THz imaging system; discuss the imaging principle of CW, data acquisition and so on, to prove the easily operated, compact, relative fast and etc. of this technology. Because the speed of data acquisition and scanning are not disagreed, the displacement is introduced in image. By changing the value of speed, acceleration of stage and position lag, the extent of displace is reduced, the system is also optimized.(2) The testing applications of CW THz imaging technology are described in detail, successfully testing mobile phone, bag of a mobile phone, hidden letters, burned glass fiber reinforced plastics, man-made defects of space shuttle insulating foam, cracks, voids and debonds in space shuttle insulating foam. Associative with the property of samples in THz range, the theoretical analyses of results are included, which proved the ability of CW THz imaging technology. Improve the image contrast of cracks detect by inserting alcohol, and discuss the influence of area, depth and edge of flaws.(3) The 0.2THz and 0.38THz system are introduced and discussed. Compare the setups and imaging characteristics theoretically and experimentally. 0.38THz system provides a higher spatial resolution; on the other hand 0.2THz system has a better signal to noise ratio. As for polyurethane foam, the absorption index of foam increases with frequency in the THz frequency range, so 0.38THz system has higher contrast in image, and 0.2THz system has less loss in propagation. Meanwhile, based on eight imaging processed algorithms, imaging results are optimized, and so more information characteristics are extracted, targets are also easily identified. At last, taking fiber glass reinforced plastics for an example, better analysis can be obtained from processed images, to avoid impossibly of analyze the original image, which improves the ability of testing of CW imaging technology.更多还原