Simulation research of terahertz coded-aperture imaging technology with high resolution

Abstract

The high resolution radar imaging has important applications in battlefield reconnaissance target detection and recognition et al.. Compared to microwave used in the conventional radar imaging, the terahertz wave has higher frequency and shorter wavelength and thus can provide larger absolute bandwidth. And the coded-aperture imaging is an expansion of the classic pinhole imaging, which has great applications in optical imaging. In this paper, we proposed a terahertz coded-aperture imaging technology with high resolution which can obtain the scattering coefficient of the target by modulating the amplitude and phase distribution of the terahertz wave. By analyzing the radiation pattern and the wave-front of the terahertz beam, we confirmed that random phase shifting can change the distribution of the wave-front to be fluctuant and generate various irradiation modes, which can provide the system with the potential for high resolution imaging and the possibility of coded-aperture imaging. To distinguish multiple scattering points in the beam, it is required that the radiation field is statistical independent in both time and space domain in one beam. After that, different targets irradiated by the seam beam will be scaled by variously distributed radiation field, and radiation echoes will contain the distinguishable information of the target distribution, which makes it possible to decouple and distinguish the target information. The more obvious spatial irrelevance the detecting signal is, the higher resolution the target cross-section imaging will be. By studying the mathematical model, we conducted a theoretic analysis of the imaging mechanism and solving method of terahertz coded-aperture imaging. And then, a simulation experiment was implemented and good results were finally obtained. The result shows that the larger range the phase shifts, the clearer image we can obtain, which proves the feasibility of high resolution imaging of the proposed method.