Overview of imaging methods based on terahertz time-domain spectroscopy

Due to the unique characteristics of terahertz (THz) waves, such as low-energy, penetrating, and broadband, THz imaging has been regarded as cutting-edge technology in many fields. As the demand for technology grows, high-performance THz imaging systems are becoming indispensable. The ability of THz time-domain spectroscopy (THz-TDS) system to extract spectra from amplitude and phase information opens virtually unlimited possibilities for imaging applications. In this review, the main performance achievements of THz-TDS imaging were displayed. The researches on fast imaging components for solving the existing deficiency of imaging speed of THz-TDS were summarized. Besides, the latest developments of several THz-TDS-based imaging methods, including tomography imaging and near-field imaging were highlighted, and an outlook on the performance improvement was presented.