Terahertz Spatiotemporal Imaging by Multiangle Beam Projection

Terahertz (THz) imaging systems have become indispensable tools for analysing the chemical and material composition of samples, driving the evolution of THz science as a distinct and expanding discipline [1]. Despite their transformative potential, THz imaging systems face critical technological limitations, particularly in achieving a wide field-of-view (FOV) and high spatial resolution imaging solutions [2]. To address these challenges, synthetic aperture imaging techniques have emerged as a promising route. The synthetic aperture approach involves capturing multiple diffraction patterns, each containing a limited spectrum of spatial frequency components, and combining them coherently to extend the system's spatial frequency bandwidth [3]. Following this, we theoretically explore the unique potential by devising a spatiotemporal, coherent synthetic aperture framework in the THz domain [4]. Our methodology, which outperforms the resolution limit in conventional THz imaging, involves synthesising an expanded spatial frequency bandpass filter scanned across the Fourier space by illuminating the sample with a broadband THz pulse at various angles. In our imaging analysis, we then incorporate a propagation of the temporal traces obtained through time-domain spectroscopy (TDS) detection, facilitating the reconstruction of the full-field response of the sample, including phase and temporal delay contributions. This approach permits us to acquire extensive spatiotemporal information on the light-matter interaction between the THz beam and the sample.