Patent ID: 7808637

Claim:
A liquid crystal viewing screen tested for defects during manufacture according to a method utilizing a computer processor for determining at least one physical parameter of a liquid crystal cell under test to determine whether said liquid crystal cell under test is defective comprising: A) directing sequences of polarization states generated by a polarization state generator at said liquid crystal cell under test, each polarization state of said sequences of polarization states differing from other polarization states of said sequences of polarization states in orientation, ellipticity and handedness, B) analyzing said sequences of polarization states as modified by said liquid crystal cell under test by a polarization state analyzer, and converting analyzed said sequences of polarization states into corresponding sequences of electrical signals, C) using said computer processor to calculate polarization properties of said liquid crystal cell under test from said sequences of electrical signals, D) using said computer to develop a computer model including at least one estimated physical parameter of said liquid crystal cell under test, and adjust said at least one estimated physical parameter until a close match is obtained between analyzed said polarization properties of said liquid crystal cell under test and calculated said polarization properties of said computer model of a liquid crystal cell, E) providing at least one indication of a closely matched said estimated physical parameter representative of a corresponding physical parameter of said liquid crystal cell under test, wherein said at least one indication further comprises indicating one or more of the group of said estimated physical parameters comprising cell gap, twist angle, rubbing direction and pre-tilt angle.