A Terahertz Transmission Imager For Teaching Experiments

Terahertz(THz)refers to electromagnetic radiation with a frequency range of 0.1 to 10 THz.The band is located between microwave and infrared,and can be used as a signal source for object imaging.Terahertz waves have better imaging resolution than microwaves,and can penetrate many objects that are opaque in the visible range,and low photon energy is harmless to the human body.This thesis mainly builds a terahertz transmission imager for teaching experiments,the working frequency is 0.3 THz.The imager selects a relatively simple structure,which reduces the complexity of adjustment and maintenance,makes the imaging system stable,low cost and easy.Promotion and other advantages.The main work of the thesis is as follows.Firstly,considering the use requirements and experimental environment of the terahertz transmission imager,selecting the appropriate coaxial system structure,designing a short focal length terahertz lens,and pre-testing the stability of the electronically controlled translation stage.The overall engineering structure of the finished product was designed by recording the basic structural parameters of the system after the initial construction.Secondly,the experimental components are introduced in detail.The workflow and interface design of the motion control and data acquisition program of the imager are introduced.The calculation of the spot radius and the principle of terahertz wave collimation in the optical path adjustment are studied,and the terahertz wave collimation is studied.With the focused beam adjustment process,a complete terahertz transmission imager was built.Finally,the basic principles of imaging are analyzed,and four key factors affecting the quality are studied: imaging position,imaging scanning interval,output intensity of the terahertz source and the placement position of the detector,and the appropriate hardware parameters of the system are determined.High-quality imaging of samples such as resolution plates,leaves,hidden objects,etc.,proves the application value of the imager.