兆赫波檢測系統研究

A Study of Terahertz Detection System

王新發(Hsin Far Wang)

指導教授 ： 周 明 博士

國立臺灣師範大學/科技學院/工業教育學系/碩士(2002年)

摘要

摘要
兆赫波(Terahertz THZ or T-ray)是頻率介於0.1至10兆赫的電磁波，相對於微波及光頻段的應用來說，是相當新且充滿潛力的領域，由於現在科技的發展朝向更高速發展，因此探討材料在兆赫波頻段的響應及光電特性成為重要的課題，且兆赫波的光子能量低屬非游離輻射，所以可以應用在醫學、生物的檢測方面，如電腦斷層、腫瘤檢測方面。
本研究的目的在探討兆赫波檢測系統的原理、組成及在電腦斷層方面的應用並增加系統網路遠端控制功能，在兆赫波的產生是使用大孔徑光電導天線的方式，檢測兆赫波則是利用碲化鋅（ZnTe）電光晶體的電光效應，系統控制部分則是透過GPIB 由LabVIEW撰寫的軟體控制。研究中對於醫學影像的檢測應用方面，則是對樣品桌球、S型塑膠、燒杯中放入塑膠棒等樣品，做兆赫波電腦斷層（Computed Tomography）影像的分析，利用樣品在各角度下兆赫波穿透樣品時振幅及相位差異為參數，經計算及濾波處理後得到樣品投影影像，再經過Matlab軟體工具作影像資料的反雷登轉換（Inverse Radon Transform）以得到兆赫波在樣品中各平面斷層的吸收情形資料、接著影像處理及重建樣品3D影像，另外修改系統軟體，增加網路遠端控制的功能，由此研究的探討希望對於兆赫波領域的認識與應用能有基礎的了解並對於進一步的研究發展奠定基礎。

關鍵字

大孔徑光電導天線 ； 碲化鋅 ； 電腦斷層

並列摘要

Abstract
Terahertz is a kind of electro-magnetic wave, the frequency of which is between 0.1 and 10 Terahertz. Compared with the application of microwave and the frequency range of light, this is a rather new and potential field. As modern technology are trending toward pursuing higher speed, the exploration of material frequency response in THz frequency range and the features of photo-electricity have become important issues. In addition, photo energy belongs to the category of non-liberated radiation, so it can be applied to material and biological tests, such as computed tomography and tumor
detection.
The purpose of the study is to explore the theory and formation of THZ detecting system and its application in computed tomography as well as to add the function of remote control to the system. The Large Aperture Photoconduction Antenna method is used in the production of THZ, which electro-optic crystal(ZnTe) is used in detecting THZ. As for the system control, it is controlled by the software programmed by LabVIEW via GPIB. In the application of detecting the medical images in the study samples of a ping-pong ball, S-shaped polyethylene, a vial with a polyethylene rod inside are analyzed by THZ computed tomography image. Make use of the magnitude and phase difference of THZ which penetrates the sample from different angles as parameter, obtain the projection of the samples through calculation and the filter process, and then acquire the data of how THZ is absorbed in every layer of the samples by processing image data through Inverse Radon Transform of the Matlab software. Next, deal with the images and reconstructed the 3D images of the samples. Apart from that, modify the system software and add the network remote-controlled function to it. Hopefully, through this study, we can have a basic understanding of realm of THZ and its application, and consequently lay the foundation of the further studies.

並列關鍵字

Large Aperture Photoconduction Antenna ； ZnTe ； Computed Tomography