LED light coupler design for a ultra thin light guide

Abstract

A LED light coupler is proposed for coupling light from a mini side LED of 0.4 mm height to a very thin (-0.3 mm) light guide. Due to the ultra thinness of the light guide, conventional light couplings between LEDs and light guides do not provide adequate coupling efficiency. The designed LED coupler is a compound lens of 3.5 mm length, 1.2 mm height, and 3.3 mm width. The coupler first collimates the light from the LED and then concentrates the light in a manner similar to a compound parabolic concentrator (CPC) into the light guide. The exit surface of the coupler is additionally textured to have micro patterns in order to control the radiance profile.