Abstract: Provided is an optical film that can eliminate rainbow unevenness when viewed with the naked eyes and provide favorable color tone uniformity when viewed at an oblique angle. This optical film has a low-refractive index layer on a plastic film, the plastic film has a slow axis that is an axis with the largest refractive index in a plane, and a fast axis that is an axis orthogonal to the slow axis in the plane of the plastic film, and the low-refractive index layer is located on the surface of the optical film. Linearly polarized light is incident, under predetermined conditions, from a surface on a side opposite to the low-refractive index layer of the optical film, and transmitted light of the linearly polarized light is used to measure the a* value and b* value of the L*a*b* color system at 11 measurement points with different angles.

Abstract: A local exposure method includes steps of: dividing a large block into a plurality of small blocks; setting irradiation illuminances different in a stepwise fashion; controlling light emission of light emitting elements based on the irradiation illuminances respectively set for the small blocks for a photosensitive film on a substrate moving with respect to light emitting elements; developing the photosensitive film having been subjected to exposure processing by irradiation by the light emitting elements; measuring a residual film thickness of the photosensitive film for each of the small blocks to obtain correlation data between the illuminance set for the small block and the residual film thickness; and obtaining a required illuminance of irradiation to each of the large blocks from a target residual film thickness of the photosensitive film set for each of the large blocks based on the correlation data.

Abstract: A local exposure method includes steps of: dividing a large block into a plurality of small blocks; setting irradiation illuminances different in a stepwise fashion; controlling light emission of light emitting elements based on the irradiation illuminances respectively set for the small blocks for a photosensitive film on a substrate moving with respect to light emitting elements; developing the photosensitive film having been subjected to exposure processing by irradiation by the light emitting elements; measuring a residual film thickness of the photosensitive film for each of the small blocks to obtain correlation data between the illuminance set for the small block and the residual film thickness; and obtaining a required illuminance of irradiation to each of the large blocks from a target residual film thickness of the photosensitive film set for each of the large blocks based on the correlation data.