Rigorous coupled-wave analysis of an optical scattering property of a light diffusing film including alternate polymer layer structure

Abstract

A high transmission and wide-angle light diffusing film for a liquid crystal display device are required. We proposed the light diffusing film including alternate polymer layer structure which diffracts light at large angles. However, the evaluation method of the refractive index distribution (RID) and analysis method of optical property do not exist. Therefore, the basic mechanism that the scattering distribution (SD) is trapezoid was not clear. In this report, we developed the noise reduction method of the reflection light distribution measured by a laser confocal microscope for using it as the RID and the evaluated RID clarified the RID was composed of several periodic structures with different amplitudes. Therefore, we extracted the periodic structures with the large amplitude and analyzed the SDs of the extracted structures on the basis of rigorous coupled-wave analysis. It was revealed that the main reason to form the trapezoidal SD was a first order diffracted light and the existence of plural periodic structures formed the constant intensity of the SD within a certain angle range.