Method of and apparatus for measuring retardation of composite layer
AssigneeNew Oji Paper Co., Ltd.
InventorsKyoji Imagawa, Shinichi Nagata, Kiyokazu Sakai
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Abstract
A compensation polarizing plate which is superior in polarization characteristic to a polarizing filter layer of a composite layer sample is arranged on the polarization filter layer side of the composite layer sample whose polarizing filter layer has an insufficient degree of polarization, and polarization transmission axes of the polarizing filter layer and the compensation polarizing plate are kept in parallel with each other to compensate the polarization characteristics of the polarization filter layer. Measurement for obtaining the retardation value and the optical principal axis direction of the sample is carried out in the state of the compensated sample.
Claims12
A method of measuring retardation of a composite layer, comprising the steps of:
- providing a composite layer sample, being obtained by stacking a polarizing filter layer with a birefringent layer, with a compensation polarizing plate on the side of said polarization filter layer and keeping polarization transmission axes of said polarizing filter layer and said compensation polarizing plate in parallel with each other thereby compensating polarization characteristics of said polarizing filter layer;
- and
- applying a measuring beam from the side of said compensation polarizing plate for passing light being transmitted through said compensation polarizing plate and said composite layer sample through an analyzer and relatively rotating the polarization transmission axis of said analyzer with respect to those of said compensation polarizing plate and said composite layer sample for detecting the relation between intensity of said light being transmitted through said analyzer and the polarization orientation of said analyzer thereby obtaining retardation and the optical principal axis direction of said composite layer sample.
An apparatus for measuring retardation of a composite layer, comprising:
- a light source part for applying a measuring beam to a measuring optical path;
- a sample holder holding a composite layer sample being obtained by stacking a polarizing filter layer with a birefringent layer in said measuring optical path;
- an analyzer being arranged and rotatably supported on a measuring beam outgoing side of said composite layer sample being held on said sample holder;
- a compensation polarizing plate being provided on a measuring beam incidence side of said composite layer sample being held on said sample holder and rotatably supported independently of said analyzer for compensating polarization characteristics of said polarizing filter layer of said composite layer sample, a polarization axis of said compensating polarizing plate being arranged in parallel with a polarization axis of said polarizing filter layer of said composite layer sample in said sample holder;
- a light receiving part for detecting intensity of light being transmitted through said analyzer through said compensation polarizing plate and said composite layer sample;
- and
- an arithmetic and control unit for calculating retardation and a optical principal axis direction of said composite layer sample from the angle of rotation of said analyzer and said intensity of said transmitted light being detected by said light receiving part.
Dependencies are inferred from the claim text.