Method of making waveguide illumination panels with alternating density extraction patterns for image display

Abstract

A method of making a wide-area waveguide illumination system includes providing a sheet of optically transmissive material having first and second broad-area surfaces and at least one light input edge, the sheet configured to guide light using total internal reflection. A two-dimensional pattern of light extraction features with variable areal density is formed on at least one of the surfaces, including alternating higher-density and lower-density light extraction areas across at least one dimension of the sheet. Distances between light extraction features in higher-density areas are generally less than distances between features in lower-density areas. One or more solid-state light sources are provided to illuminate the light input edge such that emitted light is guided within the sheet and partially extracted through the pattern of light extraction features. An image print may be disposed in an energy-receiving relationship with respect to the sheet such that extracted light illuminates the print.