The angle between the optical axis of a nematic liquid crystal and the inner surface of the cell strongly influences the electro-optical performances of the liquid crystal display devices. We report an accurate method to quickly determine the tilt bias angle of an anti-parallel liquid crystal cell using our spatial photometer EZContrast. The measurement system provides instant observation at an infinite distance, without mechanical scanning, of the interference figure obtained with the sample in a plus or minus 80 degree measurement angle. The tilt bias angle and the cell gap are deduced by fitting the intensity extrema of the figure. Thanks to the large set of data, it is also possible to know the error due to misalignment between the cell normal and the EZContrast axis and, consequently, this method is not influenced by the operator skill.

Date Published: 16 September 1999
PDF: 6 pages
Proc. SPIE 3826, Polarization and Color Techniques in Industrial Inspection, (16 September 1999); doi: 10.1117/12.364329

Published in SPIE Proceedings Vol. 3826:
Polarization and Color Techniques in Industrial Inspection
Elzbieta A. Marszalec; Emanuele Trucco, Editor(s)