Phase-Sensitive Single-Pixel THz Imaging Using Intensity-Only Measurements

We present a submillimeter-wave phase-sensitive imaging system by using single-pixel, intensity-only measurements. We implement this unique modality by utilizing the photoelectric effect on a high-resistivity silicon wafer illuminated by visible light from a commercial liquid crystal display projector. Randomly distributed mask patterns (16 x 16 pixel) are generated using two levels of light intensity projected on a high-resistivity silicon wafer. The spatial modulation of the amplitude and phase of the incident terahertz is achieved via the photoelectric effect, resulting in the random modulation of the object beams phase fronts accordingly. Subsequently, intensity-only measurements are collected by using a single-pixel sensor for each of the random mask patterns, and the Phaselift algorithm is applied to reconstruct the magnitude and phase of the 16 x 16 pixel image. We also demonstrate that the phase image of the scene shows superior contrast to the intensity image and offers thickness discernibility of a paper object down to 190 mu m at 690 GHz.