Real-time reflection imaging with terahertz camera and quantum-cascade laser

A real-time reflection imaging employing a terahertz (THz) camera as the imager and a 3.9 THz quantum-cascade laser (QCL) as the light source is demonstrated. The imaging light is collected and guided by only one off-axis parabolic mirror. The imaging distance is about 1 m. THz images of a coin and a knife are acquired and analyzed. An actual spatial resolution with a value of about 0.33 mm is achieved.