Continuous Terahertz Wave Imaging Technology For Detection Of Applied Research

The terahertz (THz) radiation occupies a large portion of the electromagnetic spectrum between the microwave and infrared bands. Since it possesses many attractively characteristic properties, THz imaging and sensing technologies can provide information not available through conventional methods such as microwave and X-ray techniques. THz waves contain rich information involved in molecular vibration and rotation, and have sub-picoseconds pulse width, low photon energy, and high space-time coherence. Because its'special characteristics, THz imaging technology has huge application potentiality in biological medicine, security inspection, testing of aerospace materials and so on. With the development of semiconductor technologies, a compact, relatively fast, easily operated, and portable CW imaging system has been realized, shown its'increasing practicability ly in many application fields.This thesis mainly focuses on the CW THz imaging technology, analyzes 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 works are listed as follows:(1) Main parameters of the CW system, including best imaging location and the system resolution, were measured.(2) A hammer in carton was imaged using continuous-wave imaging system and interpretation of the experimental result is presented. The results show that this new technology can be widely used in security inspections.(3) The reason for stripe background in continuous-wave imaging is investigated and a two-box reflective system is proposed to judge the reason of stripe background. Methods to eliminate the stripe are given. One is using ideal band stop filter and another one is moving the detector backforward.(4) Improvement of the continuous wave imaging system. The programm for continuous wave imaging system is perfected, not only the .txt file but also the .jpg file can be saved. Simple image processing methods, such as binarization, edge detection, and so on, are integrated into the software to reduce data processing works. Changing the reflection continuous-wave imaging system to the transmission continuous-wave imaging system. (5) Application of the continuous wave THz imaging system for confocal imaging.