Explosive Detection Technology Based On THz Technology

Terahertz(THz,1THz=1012Hz)wave band which lies between the microwave and the far-infrared radiation is from 0.1THz to 10THz. It is the transition band from the electronics to the photonics and the last frequency window which needs to be comprehensive investigated. It is very important to study the spectra of materials in THz region since the spectra of many materials contain rich physical and chemical information. In recent years, the rapid growth of the ultrafast optoelectronic technology and the low-scale semiconductor technology provides the stable optical source and detection method for the THz wave band and also promotes the research and application of the THz technology. Because of the vibration and rotation energy levels of many explosives lie in the THz wave band, the characteristic absorption spectra of the explosives which can be detected by the THz technology can be used to analyze the physical and chemistry characteristic. The THz technology provides a brand new detection method and also makes it to be the research emphasis of the world.The first chapter of this thesis introduces the study background and significance of explosive detection based on the THz spectra technology,and the characteristic of the THz wave. The research status of the domestic and abroad is summarized, and the generation and detection of the THz wave is also simply introduced.The second chapter introduces the operating principle of the terahertz time-domain spectrum system, the analysis of the THz spectra and the sample preparation principle.In the third chapter, the THz absorption spectra of 5 kinds of explosives are given. And the author compares them with the other research institutes at home and abroad, the result shows that the tendency of the spectra and the characteristic absorption spectra are almost identical. The author detects the absorption spectra of the explosive LLM105 at 0.1-2.5THz for the first time. Because of the oscillation at the high frequency, the author uses the wavelet transform to eliminate the noise of the spectral and achieve ideal results.The fourth chapter introduces the operating principle of the Fourier transform infrared spectroscopy, and detects the THz absorption spectra of 5 kinds of explosives. Then, the author compares them with the other research institutes at home and abroad, the result shows that the tendency of the spectra and the characteristic absorption spectra are almost identical. At the same time, the author detects the absorption spectra of these explosive at 21-60THz for the first time.The fifth chapter concludes the work of the thesis and looks forward to the future of the THz spectra technology.