Optics: measuring and testing – By polarized light examination – With polariscopes
Patent
1992-03-27
1993-08-24
Rosenberger, Richard A.
Optics: measuring and testing
By polarized light examination
With polariscopes
356382, G01B 1106
Patent
active
052393658
ABSTRACT:
A thickness of a liquid crystal cell is measured by placing a liquid crystal cell having a twist angle of .theta. between a polarizer and an analyzer, by measuring the strength of transmitted light through the analyzer with the polarizing angle of the polarizer tilted by 45.degree. from the orientation of the liquid crystal cell at its entry surface, and the polarizing angle of the analyzer tilted by further 45.degree. from the orientation of the liquid crystal at its output surface, by calculating retardation d.DELTA.n from the measured light strength, and by deriving a cell thickness d from both the retardation d.DELTA.n and a known birefringence .DELTA.n of the liquid crystal cell. Since this method provides the distribution of thickness data of liquid crystal cells, good quality liquid cells with uniform construction and thus without color shade can be selected.
REFERENCES:
patent: 4269511 (1981-05-01), Erwin
patent: 4272195 (1981-06-01), Kaye
patent: 4909630 (1990-03-01), Gawrisch et al.
patent: 5172187 (1992-12-01), Brosig
"Optical Properties of General Twisted Nematic Liquid-Crystal Displays" by Hiap Liew Ong Appl. Phys. Lett. 51 (18) pp. 1398-1400, Nov. 2, 1987.
Otsuka Electronics Co., Ltd.
Rosenberger Richard A.
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