Diffraction Gratings for Uniform Light Extraction from Light Guides

TL;DR

This paper presents a theoretical method using variable sub-micron diffraction gratings to achieve uniform light extraction from light guide plates, eliminating the need for diffuser sheets in backlit displays.

Contribution

It introduces a novel approach employing variable diffraction gratings to control light extraction uniformly without additional diffusers.

Findings

Achieves uniform light extraction using diffraction gratings.

Eliminates diffuser sheets in backlit display systems.

Controls local viewing angles and emitted intensity through grating dimension variation.

Abstract

A theoretical approach for uniformly extracting light propagating through a light guide plate is developed here. Typically, liquid crystal display modalities utilize a backlit lighting system illuminated from the edge with light emitting diodes. The backlight acts as a light guide plate and is coupled with a diffuser sheet along the surface to uniformly extract the light. Our approach employs sub-micron diffraction gratings and eliminates the need for diffuser sheets, while ensuring the uniform extraction of light. The physical dimensions of the grating are varied along the surface of the light guide plate to control the diffraction efficiency, thus determining the local viewing angle and emitted intensity.