Large focal depth of THz imaging system based on quasi-Bessel beams

Jianjun Liu; Lifeng Wang; Jing Li; Wei Wang; Zhi Hong

doi:10.1117/12.869870

4 November 2010 Large focal depth of THz imaging system based on quasi-Bessel beams

Jianjun Liu, Lifeng Wang, Jing Li, Wei Wang, Zhi Hong

Proceedings Volume 7854, Infrared, Millimeter Wave, and Terahertz Technologies; 78542Z (2010) https://doi.org/10.1117/12.869870
Event: Photonics Asia 2010, 2010, Beijing, China

Abstract

THz imaging technology will be potentially used in structure's defects detection, package inspection, on line product quality control, security screening or other nondestructive testing fields. But due to its long wavelength, it is difficult to obtain high spatial resolution and large focal depth simultaneously for conventional imaging systems. In this paper, diffraction free quasi-Bessel beams are used in THz imaging system to enhance the focal depth with high spatial resolution. PE conical lenses were designed and fabricated to generate quasi Bessel beams. Numeric simulations demonstrated that with suitable parameters of the conical lens, the diffraction free propagation distance and effective focal depth of the imaging system are easily reached up to 165mm, 100mm, respectively. A THz imaging system based on quasi-Bessel beams was established, and results were in good agreement with simulations. Furthermore, the inner defects built-in artificially in phenolic foam samples with diameter of 0.4mm were figured out successfully.

Citation Download Citation

Jianjun Liu, Lifeng Wang, Jing Li, Wei Wang, and Zhi Hong "Large focal depth of THz imaging system based on quasi-Bessel beams", Proc. SPIE 7854, Infrared, Millimeter Wave, and Terahertz Technologies, 78542Z (4 November 2010); https://doi.org/10.1117/12.869870

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