Applications & early results from THz heterodyne imaging at 119 μm

The authors present a description and early measurement results from a unique CW terahertz heterodyne imaging system based around two custom fabricated 2.5 THz planar Schottky diode mixers and two commercially available optically pumped far IR lasers. One laser is used for the signal beam and supplies as much as 70 mW at 2.5 THz. The other laser acts as a local oscillator source for the two mixers. The system uses the second THz mixer, a low frequency reference oscillator and a lock-in amplifier to monitor and normalise the two lasers. The system has been employed on both biological tissues as well as materials of interest to NASA space science applications. The instrumentation is briefly described and some representative images is also presented.