Patent ID: 7952711

Claim:
A method for measuring optical birefringence of a sample, comprising: directing an optical probe beam of an input state of polarization to sequentially pass through (1) at least two adjustable input polarization rotators, (2) a sample under measurement, (3) at least two adjustable output polarization rotators and (4) an output optical polarizer; directing the optical probe beam to pass through an input optical polarization generator first before directing the optical probe beam into the at least two adjustable input polarization rotators; using the input optical polarization generator to control the optical probe beam to be at the input state of polarization, wherein the input optical polarization generator includes an input optical polarizer to receive the optical probe beam and a quarter wave plate to receive the optical probe beam from the input optical polarizer; adjusting the at least two adjustable input polarization rotators and at least two adjustable output polarization rotators to produce a plurality of different states of polarization in the optical probe beam when entering the output optical polarizer; measuring optical power levels of optical transmission of the optical probe beam through the output optical polarizer at the plurality of different states of polarization of the optical probe beam when entering the output optical polarizer; and performing a numerical processing based on the input state of polarization of the optical probe beam and the measured optical power levels at the plurality of different states of polarization on the optical probe beam when entering the output optical polarizer to determine an amount of the optical retardation of the sample and an orientation of a principal polarization axis of the sample.