Optical system for ellipsometry utilizing a circularly polarized probe beam

摘要

An ellipsometry optical system is to analyze light beams reflected from or transmitted through optical devices or materials. The ellipsometry optical system includes a light source for generating a coherent light beam; a first beam splitter for splitting the coherent light beam into two light beams; an optical frequency shifter for shifting a frequency of one of the two light beams splitted by the first beam splitter to form a reference light beam; a circular polarization converter for circularly polarizing the other of the two light beams splitted by the first beam splitter to form a probing light beam which is a circularly polarized light beam to be applied to the optical device under test; a second beam splitter for combining the reference light beam and the probing light beam that transmitted through the optical device under test; a birefringence prism for receiving a light beam combined by the second beam splitter and separating polarization components which are perpendicular with each other; and a photo detector for receiving the polarization components and converting the same to corresponding electric signals.