Iba Ayato, Ikeda Makoto, Agulto Verdad C, Mag-Usara Valynn Katrine, Nakajima Makoto
Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan.
Asahi Kasei Corporation, Shizuoka 416-8501, Japan.
Sensors (Basel). 2021 Oct 11;21(20):6732. doi: 10.3390/s21206732.
This paper describes the design and development of a cylindrical super-oscillatory lens (CSOL) for applications in the sub-terahertz frequency range, which are especially ideal for industrial inspection of films using terahertz (THz) and millimeter waves. Product inspections require high resolution (same as inspection with visible light), long working distance, and long depth of focus (DOF). However, these are difficult to achieve using conventional THz components due to diffraction limits. Here, we present a numerical approach in designing a 100 mm × 100 mm CSOL with optimum properties and performance for 0.1 THz (wavelength λ = 3 mm). Simulations show that, at a focal length of 70 mm (23.3λ), the focused beam by the optimized CSOL is a thin line with a width of 2.5 mm (0.84λ), which is 0.79 times the diffraction limit. The DOF of 10 mm (3.3λ) is longer than that of conventional lenses. The results also indicate that the generation of thin line-shaped focal beam is dominantly influenced by the outer part of the lens.
本文描述了一种用于太赫兹频率范围应用的圆柱形超振荡透镜（CSOL）的设计与开发，该频率范围对于使用太赫兹（THz）和毫米波对薄膜进行工业检测尤为理想。产品检测需要高分辨率（与可见光检测相同）、长工作距离和长景深（DOF）。然而，由于衍射极限，使用传统的太赫兹组件很难实现这些要求。在此，我们提出一种数值方法，用于设计一个尺寸为100 mm×100 mm的CSOL，使其具有针对0.1 THz（波长λ = 3 mm）的最佳特性和性能。模拟结果表明，在焦距为70 mm（23.3λ）时，优化后的CSOL所聚焦的光束是一条宽度为2.5 mm（0.84λ） 的细线，这是衍射极限的0.79倍。10 mm（3.3λ）的景深比传统透镜更长。结果还表明，细线状聚焦光束的产生主要受透镜外部部分的影响。
