Terahertz Pulsed Scanning Imaging Algorithms And Applicaion

Terahertz technology is a new direction for research and application development in the future. Terahertz wave is in a blank area between the visible light and microwave, and has a huge space for development which makes terahertz science and technology concerned. The development of femtosecond laser makes photoconductive antenna into a stable and reliable terahertz pulsed radiation source for THz imaging technology. Terahertz pulse terahertz imaging technology is a potential application area, and many countries treat terahertz imaging technology as an important strategic direction. Its impact on the entire world in the future should not be ignored.This research subject focused on terahertz pulse time-domain spectroscopy imaging algorithms and terahertz application. Firstly, we considered the situation of terahertz time-domain and frequency-domain imaging technology through lots of reference papers, and concluded the development direction of terahertz imaging. Terahertz time-domain pulse spectrometer system and experimental scan imaging system working principle is introduced in this thesis. We discussed many view modes of terahertz pulse imaging to achieve the best fit in different kinds of condition. Secondly, different terahertz pulsed imaging algorithms are tried in this thesis. We derived the data processing theory in terahertz pulse time-domain imaging, and realized the double Gaussian filter and de-convolution techniques in mathematic code. In this work, terahertz phase imaging and terahertz 3D imaging are tried. Lastly, the designed data processing platform which has our own the copyright is finished in this subject. All the algorithms and the data processing platform are verified by experiments.The works of this thesis can be concluded as follows:(1) We discussed varieties of view modes in terahertz pulse imaging system. For different samples, different view modes are prepared. What’s more, different view mode can be applied even within the same sample to get different information. This is meaningful for terahertz pulse imaging data analysis.(2) A detailed derivation of the time-domain terahertz pulse imaging data processing theory is displayed in the thesis. The double Gaussian filter and de-convolution algorithms are realized. The terahertz phase imaging and three-dimensional imaging is described as well as the experiments corresponding. Through terahertz phase imaging, we can get a more precisely reconstructed image. And the 3D image helps to analyze the internal structure of the sample.(3) Terahertz imaging technology is used for the imaging reconstruction and analysis in wheat seeds, and human dental. By the view mode of ‘peak to peak in slice’, a two-dimensional reconstructed image slice of wheat seeds at different times are obtained. From the reconstructed images, the gap structure of the seeds can be vaguely discerned. And by comparing three seeds’ slices, the corresponding state seed can be determined. In the experiment, the weak terahertz radiation is scattered by the uneven surface of human teeth. So in this article, the dental imaging results are not so good enough to apply in treatment. Nevertheless, experimental results still can distinguish necrotic teeth and healthy teeth.(4) The scalable data processing and analysis platform is designed based on the mathematical tools MATLAB, and other functions are added on. The imaging data files are tested on the new platform.In summary, this thesis studied on the terahertz time domain spectroscopy imaging algorithms and applications. The feasibility of phase imaging and three-dimensional imaging algorithm was validated by experiments. This research provides a reference for further development of terahertz imaging technology, which is helpful.