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• A terahertz compressed sensing imaging method based on line array detection is proposed. • In the experiment, the reconstruction of the letter sample is realized at a sampling rate of 16%. • The proposed technology is used to reconstruct the imaging images of the terahertz line scan system. In this paper, a terahertz compressed sensing imaging technique based on line array detection is proposed. The feasibility of the proposed terahertz compressed sensing imaging based on line array detection is verified by theoretical derivation, MATLAB and ZEMAX simulation as well as practical experiment. Firstly, we compare the traditional single-pixel compressed sensing imaging, block compressed sensing imaging and the proposed terahertz compressed sensing imaging based on line array detection by MATLAB simulation, and the results show that the proposed technique can achieve high-quality image reconstruction. Then, we import self-designed mask and lenses as well as other devices into ZEMAX to simulate the compressive sensing process of line array detection using non-sequential mode. According to the simulation results, a terahertz line array compressive sensing imaging system is built using a high-speed line-array detector. The experimental results show that the technique has higher imaging stability and the sampling process is highly generalizable to different objects. Compared with the traditional single-pixel random sampling compressed sensing method, this method greatly reduces the sampling rate and successfully reconstructs the original image at a sampling rate of 16%. We believe that the compressed sensing terahertz imaging technology based on line array detection proposed in this paper provides a new idea for terahertz multi-pixel compressed sensing imaging, which is expected to promote the development of terahertz high-resolution rapid imaging. In addition, this technology can be applied to both terahertz line and area scan imaging systems, which has great application potential in correcting image distortion caused by movement of imaging objects. [ABSTRACT FROM AUTHOR]

• Aspheric lens for large depth-of-field terahertz imaging at long distances. • Depth-of-field extension is achieved by incident light with a wide field-of-view. • Farther from the element than the Bessel beam depth-of-field start point. • Fast imaging of large targets can be achieved with multipixel terahertz detectors. Terahertz (THz) imaging can serve as a versatile instrument to disclose contents of various packages or items hidden under clothing. When imaging a large target with a certain thickness at a long distance, the requirements for the imaging speed and imaging quality of the system are particularly worthy of attention. To tackle these problems and extend an assortment of application, this paper proposes a wide field-of-view (FOV) aspheric lens suitable for rapid imaging systems for extending the depth-of-field (DOF) of THz imaging at long distances. The designed aspherical lens with a diameter of 264 mm – made of high-density polyethylene (HDPE) and manufactured by machining – allows extending the DOF up to 85 mm by separately focusing incident light with different FOV angles, which not only allows fast THz imaging combined with linear array detector but also refuses the use of complicated imaging optical paths. A reflective one-dimensional (1D) scanning imaging system with a 0.1 THz source reveals that the lens can simultaneously achieve wavelength-level resolution and a DOF range of 85 mm for objects at a distance greater than 415 mm from the lens surface in a wide-field illumination system, in which the contrast of the obtained results can reach more than 15%. The observed results justify the application value of the lens in long-distance, wide-field THz imaging systems. [ABSTRACT FROM AUTHOR]