Development of optical fiber-coupled terahertz endoscope

We developed optical fiber-coupled terahertz (THz) endoscope system which utilized a photoconductive generator and detector driven by a mode-locked Ti:sapphire laser. For a feasibility test, the endoscopic system was used to measure reflective THz signals from the side wall of the mouth, tongue, and palm of hand as well as from water for comparison. The absorption and refractive index of the side wall of the mouth and tongue were similar to those of water but those of the palm of hand were less than water.