Structured Illumination for Super-Resolution Terahertz Imaging

In this thesis, advanced imaging techniques from the field of microscopy are adopted to perform structured illumination super-resolution imaging at the terahertz (THz) frequency band (0.1-10 THz). Through the use of a structured sinusoidal illumination, higher spatial frequency information that is inaccessible via diffraction-limited widefield imaging is encoded into our images. A Fourier-based reconstruction algorithm produces an image with a resolution better than that allowed by the diffraction-limit. For this work, a recently demonstrated, novel 0.55 THz imaging system that performs efficient THz-to-optical conversion using a room-temperature vapour of excited caesium atoms is used. Such a system offers kilohertz framerate speeds, enabling the exploration of these advanced imaging techniques that have, until now, been overlooked at the THz band. This work will explore the concepts, theory and experimental implementations of two super-resolution imaging techniques and demonstrate an image resolution improvement of when compared to diffraction-limited widefield imaging.