Scanning laser terahertz near-field reflection imaging system

We developed a scanning laser terahertz (THz) near-field reflection imaging system using a fiber-coupled femtosecond laser source for high spatial resolution measurements without any sub-wavelength probes. In this system, THz wave pulses generated at the laser focusing spot in a non-linear optical crystal interact with a sample set on the crystal. Using this system, we obtained the THz reflection images of metallic structures with a resolution of similar to lambda(THz)/34 (lambda(THz) = 680 mu m) and also observed paraffin-embedded human breast tissue of several 10 mu m in size. These results promise that this system can be suitable for industrial applications which require micron-scale resolution. (C) 2019 The Japan Society of Applied Physics