Fig. 1. Schematic of the real-time imaging system with a compact terahertz laser.

Fig. 2. (a) Optical and (b) terahertz images of water and water stains on an HDPE sample cell.

Fig. 3. (a) Optical and (b) terahertz images of a dried leaf on an HDPE sample plate.

Fig. 4. (a) Optical and (b) terahertz images of two human hairs and a metal wire (bent into number eight).

Fig. 5. (a) Transmission amplitude of a cross section of the terahertz image in (b); the red short dashed line indicates the detailed location.