Fast terahertz imaging with a quantum-cascade laser and a scanning mirror

A terahertz imaging system based on a quantum-cascade laser (QCL), a fast scanning mirror, and a sensitive Ge:Ga detector is demonstrated. Transmission images are obtained by scanning the beam of the QCL across an object. Images with a diameter of approximately 45 mm and a signal-to-noise ratio of approximately 25 dB were obtained within 1.1 s. The system was also used to obtain three dimensional images by computed tomography