Measurement of the Maximum Detectable Range of a THz-TDS System Driven by a Mode-Locked Laser Diode with a Divergent Beam

We measure the maximum detectable distance and frequency range of an ultra-high repetition rate terahertz time-domain spectroscopy system in reflection geometry with conductive and dielectric samples, respectively. All measurements are performed without lenses or mirrors and thus with a divergent beam. We show that frequencies up to 600 GHz are detectable at a range of 1.2 meters. The measurements are in agreement with the expected theoretical values. This enables short-range radar imaging.