Material Evaluation with Optical Measurement Systems: Focusing on Terahertz Spectroscopy

Abstract

The word “light” evokes the color which can be recognized with eyes, i.e., visible light in the wavelength range between 350 nm and 700 nm. The shorter and longer wavelength’s regions are called as ultraviolet and ultrared, respectively. The wavelength of light represents the energy state, that is to say, the light at the shorter wavelength corresponds to higher energy state and the longer does to lower. Generally, the absorbance in the UV-Vis region is caused by the electron transition. The absorbance in infrared region is derived from molecular vibration and rotation.