Coherent reconstruction of a textile and a hidden object with terahertz radiation

Imaging through scattering materials is of utmost importance, especially for security and biomedical imaging. Unlike the rest of the electromagnetic spectrum, terahertz radiation is a non-ionizing probe and allows imaging deep through non-conducting materials with sub-millimeter resolution. Here, we propose a coherent imaging technique reconstructing two objects, hidden one behind the other, from relative shifts between them. Experimental reconstructions at lambda = 96.5 mu m of amplitude and phase objects hidden behind a glass fabric sample are presented. The hidden objects are retrieved with a lateral resolution of approximate to 1.5 lambda and a depth resolution of approximate to lambda/10. Besides envisioning its use in noninvasive imaging, we anticipate that, in selected applications, the suggested approach can replace a similar phase retrieval technique, namely ptychography. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement