Abstract

Terahertz light is expected as a promising light source for a new nondestructive testing system because it can penetrate some materials into which visible light cannot penetrate, such as papers, plastic resins, and a silicon. Particularly, polarization information of the terahertz light can be used for the measurement of the photoelasticity and the circular dichroism, which can be applied to the nondestructive quality inspection of plastic parts and optically active medicines. Recently, a variety of techniques utilizing the polarization information of the terahertz light are published. For example, a measurement of the complex dielectric constant spectrum was done by the terahertz time-domain spectroscopic ellipsometry [1], and the terahertz circular dichroism was done for biomolecules [2]. We also developped the spinning electro-optic crystal sensor method which can be used to measure the polarization property of the terahertz light [3]. But for the in-line inspection, the measurement speed is required to be quicker and more accurate.

© 2015 IEEE