Realization of active terahertz imaging system

A fast scanning terahertz (THz) active imaging system was conducted for nondestructive testing and safety inspection, and its practical applicability was discussed. The system used a solid state THz source and it was focused and illuminated on the object to be tested. The reflected THz signal was collected by the optical system, and was focused on an antenna coupled microbolometer operating at room temperature. The image of the object was gotten by two dimensional mechanical scanning. The scanning mirror was an aluminum flat mirror fixed on a servo motor, and the servo motor was fixed on an electronically controlled rotational stage. The system was controlled by a LabVIEW program. When a single pixel detector was used, the highest frame rate is 1 frame/s for a image with the size of 40×40. Moreover, the theoretical resolution is 4.7 mm at 0.65 THz and 1.41 cm at 0.22 THz. The result shows that the system has reached the expected performance.