We report a technique using photo-induced coded-aperture arrays for potential real-time THz imaging at roomtemperature.
The coded apertures (based on Hadamard coding) were implemented using programmable illumination on
semi-insulating Silicon wafer by a commercial digital-light processing (DLP) projector. Initial imaging experiments
were performed in the 500-750 GHz band using a WR-1.5 vector network analyzer (VNA) as the source and receiver.
Over the entire band, each array pixel can be optically turned on and off with an average modulation depth of ~20 dB
and ~35 dB, for ~4 cm2 and ~0.5 cm2 imaging areas respectively. The modulation speed is ~1.3 kHz using the current
DLP system and data acquisition software. Prototype imaging demonstrations have shown that a 256-pixel image can be
obtained in the order of 10 seconds using compressed sensing (CS), and this speed can be improved greatly for potential
real-time or video-rate THz imaging. This photo-induced coded-aperture imaging (PI-CAI) technique has been
successfully applied to characterize THz beams in quasi-optical systems and THz horn antennas.