Augustin Sven, Frohmann Sven, Jung Peter, Hübers Heinz-Wilhelm
Department of Physics, Humboldt Universität zu Berlin, Berlin, 12489, Germany.
Department of Optical Sensor Systems, German Aerospace Center Berlin - Adlershof, Berlin, 12489, Germany.
Sci Rep. 2018 Mar 20;8(1):4886. doi: 10.1038/s41598-018-23313-6.
Terahertz (THz) radiation meaning electromagnetic radiation in the range from 0.1 (3) to 10 (30) has the unique advantage of easily penetrating many obstructions while being non-hazardous to organic tissue since it is non-ionizing. A shortcoming of this domain is the limited availability of high-sensitivity detector arrays respective THz cameras with >1k pixels. To overcome the imaging limitations of the THz domain, compressive imaging in combination with an optically controllable THz spatial light modulator is a promising approach especially when used in a single-pixel imaging modality. The imaging fidelity, performance and speed of this approach depend crucially on the imaging patterns also called masks and their properties used in the imaging process. Therefore, in this paper, it is investigated how the image quality after reconstruction is specifically influenced by the different mask types and their properties in a compressive imaging modality. The evaluation uses an liquid-crystal display based projector as spatial light modulator to derive specific guidelines for the use of binary and true greyscale masks in THz single-pixel imaging setups respective THz single-pixel cameras when used in far-field applications e.g. stand-off security imaging.
太赫兹（THz）辐射是指频率范围在0.1（3）至10（30）的电磁辐射，具有独特优势，因其是非电离的，所以能轻松穿透许多障碍物，同时对有机组织无害。该领域的一个缺点是高灵敏度探测器阵列以及像素超过1k的太赫兹相机数量有限。为克服太赫兹领域的成像限制，将压缩成像与光学可控太赫兹空间光调制器相结合是一种很有前景的方法，特别是在单像素成像模式中使用时。这种方法的成像保真度、性能和速度关键取决于成像过程中使用的成像图案（也称为掩模）及其特性。因此，本文研究了在压缩成像模式下，不同掩模类型及其特性如何具体影响重建后的图像质量。评估使用基于液晶显示器的投影仪作为空间光调制器，以得出在太赫兹单像素成像装置或太赫兹单像素相机用于远场应用（如远距离安全成像）时，使用二进制和真灰度掩模的具体指导原则。
