| 摘要 |
An optical film is provided, which displays a positive wavelength dependency across the entire wavelength region from 400 to 800 nm, and is capable of imparting a specified retardation to transmitted light with a single sheet of film. The optical film particularly, includes a thermoplastic norbornene-based resin with a specified structure formed of a structural unit (I) which imparts a positive birefringence and a structural unit (II) which imparts a negative birefringence, and which satisfies particular conditions with respect to DeltaN<SUB>I</SUB>(lambda), DeltaN<SUB>II</SUB>(lambda), DeltaN<SUB>I</SUB>(800) and DeltaN<SUB>II</SUB>(800) wherein DeltaN<SUB>I</SUB>(lambda) and DeltaN<SUB>II</SUB>(lambda) represent the difference between a refractive index Nx(lambda) in an x axis direction at a wavelength lambda, and a refractive index Ny(lambda) in a y axis direction, and DeltaN<SUB>I</SUB>(800) and DeltaN<SUB>II</SUB>(800) represent the difference in refractive indexes at a wavelength of 800 nm, and the x axis represents the stretching direction and the y axis represents the in-plane direction perpendicular to the x direction. |
