Terahertz time domain spectroscopy device

A terahertz time domain spectroscopy device provided with a liquid sample in a path through which a terahertz wave is propagated and performing time domain spectroscopy measurement over a property of a terahertz wave transmitted through the liquid sample, comprising:

• a terahertz wave spectral dispersing unit for spectrally dispersing a terahertz wave to be generated from a terahertz light source into two waves;
• a terahertz wave focusing unit for focusing a terahertz wave transmitted through a sample liquid film provided in a path through which one of terahertz waves obtained by spectral dispersion through the terahertz wave spectral dispersing unit is propagated and a terahertz wave transmitted through a reference liquid film provided in a path through which the other terahertz wave obtained by the spectral dispersion through the terahertz spectral dispersing unit is propagated;
• and
• a terahertz wave detecting unit for detecting a terahertz wave focused by the terahertz wave focusing unit.