Continuous-wave Terahertz Imaging Experimental Study

Terahertz (THz) waves refer to the electromagnetic radiation with the frequency range of 0.1THz to 10THz (wavelength range of 30μm to 3mm ), which the wave band is between millimeter and infrared ray, and is the transition area from the macroscopic electromagnetic theory to the microcosmic quantum theory. Terahertz science and technology has important academic application and research value. As the THz source has successfully developed, the terahertz science and technology would be well developed science the 80s of 20 centuries. Yet so far, because of lacking the electronic devices that can work in THz band, the THz technology meets somewhat difficulties.Terahertz imaging is a new technology of imaging.It has more higher image resolution than the microwave imaging,and has more stronger penetration ability than light. It has lower energy than X-rays.There are not any damage to human body.It can be used to military,security,medical,biological imaging and so on.It have broad application prospects.The following results have been achieved in this thesis:First,a scanning imaging control system has been designed using LabVIEW software in order to realize synchronization of sample location and image data acquisition.Second,several continuous wave THz imaging data processing programs have been writed by using MATLAB,which mainly incolude real-imaging,one-dimensional scaning imaging,two dimensional scaning imaging.Third, the relationship between imaging resolution and samples scanning speed has been studied ,while relationship between imaging resolution and samples thickness. The transmission effects of different samples have been compared for terahertz wave.The effects of imaging data processing have been compared by using directly images processing and average images processing,the results shown that average image processing has more better resolutions.Finally, The transmission effects of polyethylene and paper have been compared in experiments about two-dimensional Continuous wave THz imaging scanning imaging,The results show that the effect of imaging have very big relation with materials.The polyethylene has more better resolution than paper in the transmission imaging experiments.