Terahertz Stand-Off Imaging for Security Applications

Date

2023-9-05

Author

Yıldırım, İhsan Ozan

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Terahertz (THz) and millimeter wave (MMW) imaging techniques has been the subject of extensive research for applications in a wide range of areas such as security, medicine, material characterization, and product quality control. This interest is motivated by their unique properties such as the ability to penetrate through barrier materials. They have proven valuable in detecting contraband, illicit drugs and explosives in security applications. Also in the security domain, THz and MMW technologies have been utilized for biometric purposes, involving the recognition of users based on their physiological and/or behavioral attributes. This thesis presents an active THz stand-off imaging system developed for security applications. System uses Schottky diode mixers and multipliers for generation and detection of THz radiation at 340 GHz frequency, with a transceiver unit in frequency modulated continuous wave (FMCW) operation. Two main applications in the field of security are presented in this thesis. First one is concealed object detection based on full-body images of individuals. It has been shown that the choice of operating frequency, optical design and signal characteristics of the system possess sufficient spatial and contrast resolution which allow detecting and localizing objects through barrier materials. These capabilities of the system is also utilized for recognition of concealed faces, in the field of biometrics. The study presented here is the first ever of its kind demonstrating the identification of concealed faces using THz radiation. The success rate of the developed recognition method is over 85%. Recognition of concealed faces can be extremely useful for future applications in border control and security.

Subject Keywords

terahertz imaging, scanned imaging system, concealed object detection, face recognition

URI

https://hdl.handle.net/11511/105589

Collections

Graduate School of Natural and Applied Sciences, Thesis