Abstract-Single-pixel terahertz imaging based on spatial Fourier spectrum

Rongbin She, Wenquan Liu, Yuanfu Lu, Zhisheng Zhou, Guangyuan Li

http://export.arxiv.org/abs/1812.06767

We propose and demonstrate single-pixel terahertz imaging based on spatial Fourier spectrum (SFS). The concept and the operation principle of this novel approach are introduced by comparing with the conventional compressing sensing (CS) approach, clarifying their similarities and differences. By doing this, we find that these two different approaches can share the same photo-induced coded aperture setup, facilitating their direct comparisons. Our results show that, compared with the CS approach, the SFS approach can reconstruct high-quality images with greatly reduced number of measurements, i.e., the sampling ratio, and is thus more efficient. Remarkably, the SFS-based system is capable to assemble a 64x64 image with signal-to-noise ratio of 6.0 for a sampling ratio of only 4.8%. We further show that deep photo-induced terahertz modulation by adopting graphene on silicon substrate and high laser power can significantly improve the image quality. We expect this work will speed up the efficiency of single-pixel THz imaging and advance THz imaging applications.

Abstract-Mask Responses for Single-Pixel Terahertz Imaging

Sven Augustin, Sven Frohmann, Peter Jung, Heinz-Wilhelm Hübers

https://www.nature.com/articles/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.