Terahertz Wave Sensing Technology for Visualizing Hidden Objects

When sensing the shape and movement of objects in the near field, light waves and radio waves have been used as the medium so far. Methods using light waves include sensors such as cameras and ToF (Time of Flight) sensors, which can achieve high-resolution sensing. However, light waves are weak to shielding and greatly affected by obstacles, making it difficult to sense hidden objects. On the other hand, radio waves have superior transmission performance compared to light waves, but due to their long wavelength, it is difficult to secure resolution. Therefore, in recent years, terahertz waves have been attracting attention as a sensing medium that combines the features of both light waves and radio waves. Terahertz waves are electromagnetic waves with a frequency located between light waves and radio waves, from 100 GHz to 10 THz. They can sense targets behind obstacles with high accuracy and high resolution, and are particularly expected to be applied in fields related to safety and security, such as body scanners and infrastructure inspections. Also, a feature of the terahertz band is that it can achieve high-precision tomographic imaging using wideband radar signals. In this paper, we describe the configuration of the proposed terahertz wave tomographic imaging system, show the results of principle verification experiments using the 300 GHz band, and discuss high-precision design techniques for 300 GHz band integrated circuits and their application examples.