Status of three-dimensional terahertz Fourier imaging for industrial application [Invited]

Terahertz (THz) radiations span the transition region between microwave and infrared frequencies, with a unique combination of very useful attributes and mm scale imaging resolution capability. THz imaging, therefore, has the potential to enhance quality assurance and inspection processes, helping industries maintain high standards and improve operational efficiency. In recent times, through a combination of artificial intelligence algorithms and advanced and rapid acquisition techniques, THz imaging is increasingly becoming viable for more accurate defect detection and material characterization with augmented data analysis capabilities. In this present work, we provide a detailed review of one such advanced THz imaging technique, that is, THz Fourier imaging, which is capable of providing three-dimensional (3D) information of the scenery being imaged where the THz field is recorded in the frequency domain through a coherent diffraction technique. We also show that this technique is compatible with advanced computational sensing such as super-resolution, digital auto-focusing, compressed sensing, etc., which makes this 3D THz Fourier imaging an extremely efficient and a capable characterization tool in diverse industrial applications.