Hu Weidong, Xu Zhihao, Jiang Huanyu, Liu Yang, Yao Zhiyu, Zhang Kaiqi, Ligthart Leo P
Appl Opt. 2022 Aug 20;61(24):7189-7196. doi: 10.1364/AO.465647.
Terahertz frequency modulation continuous wave (THz FMCW) imaging technology has been widely used in non-destructive testing (NDT) applications of non-metallic materials. However, THz FMCW real-aperture radar usually has a narrow bandwidth and small depth of field, thus restricting the application of THz FMCW NDT. In this paper, a wideband THz signal (220-500 GHz) generation method is proposed by time-division multiplexing. Moreover, a dual-band quasi-optical design with a large depth of field is proposed based on the THz Bessel beam, and a high-quality range profile is obtained. Especially, a signal fusion extended Fourier analysis algorithm without prior knowledge is proposed to further enhance the range profile accuracy, which improves the range resolution to 0.28 mm (/3, center frequency 360 GHz). The effectiveness and advantages of the proposed system are verified by artificially constructing composite materials.
太赫兹调频连续波（THz FMCW）成像技术已广泛应用于非金属材料的无损检测（NDT）应用中。然而，太赫兹FMCW真实孔径雷达通常具有窄带宽和小景深，从而限制了太赫兹FMCW无损检测的应用。本文提出了一种时分复用的宽带太赫兹信号（220 - 500 GHz）产生方法。此外，基于太赫兹贝塞尔光束提出了一种具有大景深的双波段准光学设计，并获得了高质量的距离像。特别是，提出了一种无需先验知识的信号融合扩展傅里叶分析算法，以进一步提高距离像精度，将距离分辨率提高到0.28毫米（λ/3，中心频率360 GHz）。通过人工构建复合材料验证了所提系统的有效性和优势。
