Optics: measuring and testing – By polarized light examination
Patent
1996-06-21
1998-03-31
Font, Frank G.
Optics: measuring and testing
By polarized light examination
356365, 356367, G01N 2121
Patent
active
057344728
ABSTRACT:
A liquid crystal layer is interposed between two polarizers arranged in a parallel Nicol or crossed Nicol manner, and a phase plate is set between two polarizers so that the transmission direction of the first polarizer coincides with the optical axis. Then, a rotation angle at which optical intensity transmitted through the second polarizer has an extreme value to be determined, and the thickness of the birefringence layer is calculated according to the rotation angle of the phase plate. In a different method, a half-wave plate is used. First, the liquid crystal layer is set at a position where an optical intensity of the transmission light has an extreme value, and the half-wave plate provided between the two polarizers is set so that a transmission direction of the first polarizer coincides with the optical axis. Then, a rotation angle of the phase plate is determined at which an optical intensity of light transmitted through the second polarizer has an extreme value. Then, the thickness is calculated according to the rotation angle of the half-wave plate. Thus, the thickness is measured in a short time even for a liquid crystal that does not have a twist angle of 90.degree. or in which the rubbing direction is not known.
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Fukui Atsushi
Ito Masami
Nishii Kanji
Takamoto Kenji
Font Frank G.
Matsushita Electric - Industrial Co., Ltd.
Stafira Michael P.
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