2 February 2009 High speed imaging with CW THz for security
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Continuous THz wave (CW THz) has been widely used in imaging field. But for security screening such as inspection at the airport, the speed of the imaging calls for an improvement since the former CW image systems which scan point to point could not satisfy. To increase the image speed, we proposed a fast CW THz image system in which a galvanometer is introduced for the first time. The galvanometer makes the coming beam reflected in different angles by vibrating at a certain frequency which can significantly decrease the image acquisition time compare to point scan THz imaging. A big hyperbolic polyethylene lens is also used in the system to collect all the beams on to the target. A Gunn oscillator and a corresponding Schottky diode are the source and detector respectively. The image we get has ideal resolution. And after image processing, the images looked not only clear but also realistic. The system has more practicality because it is designed in reflection geometry instead of transmission geometry. Moreover, the source and detector in our system do not as ponderous as gas laser which has been used in many THz imaging system previously. Example of measurements of weapons concealed behind the cloth and box are presented and discussed. A compact high speed THz imaging system is expectable which will have a widely application in security field.
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Qian Song, Qian Song, Albert Redo-Sanchez, Albert Redo-Sanchez, Yuejin Zhao, Yuejin Zhao, Cunlin Zhang, Cunlin Zhang, } "High speed imaging with CW THz for security", Proc. SPIE 7160, 2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 716016 (2 February 2009); doi: 10.1117/12.807197; https://doi.org/10.1117/12.807197

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