Method and apparatus for measuring parameters of optical anisotropy

Abstract

Methods and systems are provided to measure the optical anisotropy properties of a film on glass or other substrates. This technique is suitable for production environments, and is not strongly affected by the TFT or CF active area on LCD panels, even for very high pixel density displays. A method is provided for measuring a magnitude and orientation of optical anisotropy. These methods and systems include an optical anisotropy measurement apparatus for measuring anisotropic materials in a reflection or transmission configuration. The methods and systems may measure a Mueller matrix, diattentuation orientation, or retardance of a sample at one or more rotation angles to calculate anisotropic magnitude and orientation.

What is claimed is: 
     
         1 . A method in an apparatus for measuring optical anisotropic properties of a material, comprising:
 measuring one of: (1) a Mueller matrix of the material, (2) diattenuation orientation of the material, and (3) retardance magnitude of the material; and   determining a value proportional to anisotropic magnitude of the material based on the measured one of: (1) the Mueller matrix of the material, (2) the diattenuation orientation of the material, and (3) the retardance magnitude of the material.   
     
     
         2 . The method of  claim 1 , further comprising determining anisotropic orientation for the material based on the measured one of: (1) the Mueller matrix of the material, (2) diattenuation orientation of the material, and (3) retardance magnitude of the material. 
     
     
         3 . A method in an apparatus for measuring optical anisotropic properties of a material, comprising:
 measuring a Mueller matrix of the material at a first angle;   determining the diattenuation orientation of the material based on the measured Mueller matrix at the first angle;   rotating the material to a second angle;   measuring a Mueller matrix of the material at the second angle;   determining the diattenuation orientation of the material based on the measured Mueller matrix at the second angle;   storing a data set of the determined diattenuation orientations and the first and second angles;   curve fitting a formula to the stored data set of determined diattenuation orientations and the first and second angles to determine fitting parameters; and   determining anisotropic orientation and a value proportional to anisotropic magnitude of the material using the determined fitting parameters.   
     
     
         4 . The method of  claim 3 , further comprising:
 repeatedly performing:
 (1) rotating the material to a different angle, 
 (2) measuring a Mueller matrix of the material at the different angle, and 
 (3) determining the diattenuation orientation of the material based on the measured Mueller matrix at the different angle. 
   
     
     
         5 . An apparatus for measuring optical anisotropic properties of a material, comprising:
 a polarimeter configured to:
 measure a Mueller matrix of the material; and 
   a processor configured to:
 determine a value proportional to anisotropic magnitude of the material based on the measured Mueller matrix of the material. 
   
     
     
         6 . The apparatus of  claim 5 , further comprising determining anisotropic orientation for the material based on the measured Mueller matrix of the material. 
     
     
         7 . An apparatus for measuring optical anisotropic properties of a material, comprising:
 a polarimeter configured to:
 measure a Mueller matrix of the material at a first angle; and 
 measure a Mueller matrix of the material at the second angle; 
   a rotating fixture configured to:
 rotate the material to a second angle; and 
   a processor configured to:
 determine the diattenuation orientation of the material based on the measured Mueller matrix at the first angle; 
 determine the diattenuation orientation of the material based on the measured Mueller matrix at the second angle; 
 store a data set of the determined diattenuation orientations and the first and second angles; 
 curve fit a formula to the stored data set of determined diattenuation orientations and the first and second angles to determine fitting parameters; and 
 determine anisotropic orientation and a value proportional to anisotropic magnitude of the material using the determined fitting parameters. 
   
     
     
         8 . The apparatus of  claim 7 , wherein the apparatus repeatedly performs:
 (1) rotating, by the rotating fixture, the material to a different angle,   (2) measuring, by the polarimeter, a Mueller matrix of the material at the different angle, and   (3) determine, by the processor, the diattenuation orientation of the material based on the measured Mueller matrix at the different angle.   
     
     
         9 . A method in an apparatus for measuring optical anisotropic properties of a material, comprising:
 measuring a Mueller matrix of the material; and   determining a value proportional to anisotropic magnitude of the material based on the measured Mueller matrix of the material.