Synthetic Photoconductive Antenna Array for Terahertz 3-D Imaging and Spectroscopy

We propose a 3-D imaging and spectroscopy approach in the terahertz (THz) domain based on the synthetic aperture imaging technique achieved using a time domain spectroscopy system. The proposed system enables the imaging and spectroscopy of an object in a stationary position in a transmission configuration. We demonstrate the reconstruction of 3-D amplitude images with a submillimeter resolution of a multi-material object from 0.6 to 1 THz using the back-projection algorithm. The reconstructed data is further used to characterize the optical properties of the substrates forming the object by calculating the refractive index and the absorption coefficient of its constituents in the reconstruction frequency band. We demonstrate the use of the SA not only for imaging but also for material characterization. Consequently, we are able to reconstruct 2-D high-resolution spectral maps of the real refractive index at different THz frequencies of the imaged object.