Synthetic aperture imaging with pulsed terahertz waves and its application in three-dimensional modeling of complex structures

In this study, we report a three-dimensional synthetic aperture imaging system realized by a terahertz time-domain spectrometer. The temporal waveforms of the terahertz pulses scattered by the object to be imaged are Fourier transformed to the frequency domain before image reconstruction by the back-projection algorithm. The resolution of the imaging system is close to the center wavelength of the terahertz pulses, as tested by a resolution test chart. We also demonstrate the ability of this imaging method in non-destructive evaluation applications by measuring the internal structures of a university badge. A three-dimensional terahertz image and a series of slice views of the badge are acquired. The terahertz images clearly show the surface shape and internal structures of the badge, and the logo of the university on the badge is successfully extracted from the three-dimensional terahertz image.