Abstract: The present invention relates to a phase retardation plate including a thin organic film with a phase retardation function due to birefringence and a fixed substrate bonded to at least one surface of the thin organic film using an adhesive, and to an optical pickup device having the phase retardation plate. In the phase retardation plate and the optical pickup device using the same, a liner thermal expansion coefficient (L1) of the thin organic film, a liner thermal expansion coefficient (L2) of the adhesive and a liner thermal expansion coefficient (L3) of the fixed substrate satisfy a relationship of L1>L2>L3; and the thin organic film retards the phase of incident light with a wavelength in a range of 400 to 800 nm by ?/2 or ?, the thin organic film having a phase retardation value between 0 and ?.

Abstract: An optical film includes a first refraction layer having a first surface with first optical lens patterns for scattering light and a second surface opposite to the first surface, the first optical lens patterns having a lens shape, and a second refraction layer on the first surface and having second optical patterns for redirecting light in a first direction that is perpendicular to the second surface of the first refraction layer, the second optical patterns being linearly arranged.

Abstract: The present invention relates to an optical film for a backlight unit and a method for manufacturing the same. The optical film of the present invention comprises a light diffusion layer in which light diffusing particles are distributed, a first refraction layer which has a relatively low index of refraction and is formed integrally on a top surface of the light diffusion layer, and a second refraction layer which has an index of refraction relatively higher than that of the first refraction layer and is formed integrally on a top surface of the first refraction layer and formed with a refraction pattern on a surface thereof. According to the present invention, the loss of light can be prevented, the adsorption of foreign substances in and the resultant scratch generation on the films can be avoided during the assembly process of the backlight unit, the productivity improvement and manufacturing cost reduction can be achieved, and the brightness of the backlight unit can be adjusted.