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

A method of making a wide-area waveguide illumination system, the method comprising:

• providing a sheet of optically transmissive material having a first broad-area surface, an opposing second broad-area surface, and at least one light input edge, the sheet configured for guiding light using total internal reflection;
• forming, on at least one broad-area surface, a two-dimensional pattern of light extraction features, the two-dimensional pattern having variable areal density and comprising higher-density and lower-density areas, wherein distances between the light extraction features in the higher-density areas are generally less than distances between the light extraction features in the lower-density areas;
• and
• providing one or more solid-state light sources configured to be optically coupled to the at least one light input edge such that, when coupled to the at least one light input edge, light emitted from the one or more solid-state light sources is guided within the sheet and extracted by the two-dimensional pattern of light extraction features,
• wherein the two-dimensional pattern of light extraction features includes at least first, second, and third of the higher-density areas located progressively farther from the at least one light input edge and separated from one another by one or more of the lower-density areas, and
• wherein an areal density of the first of the higher-density areas is less than an areal density of the second of the higher-density areas, and the areal density of the second of the higher-density areas is less than an areal density of the third of the higher-density areas.

A method of making a wide-area waveguide illumination system, the method comprising:

• providing a sheet of optically transmissive material having a first broad-area surface, an opposing second broad-area surface, and at least one light input edge, the sheet configured for guiding light using total internal reflection;
• forming, on at least one broad-area surface, a two-dimensional pattern of light extraction features, the two-dimensional pattern comprising patterned areas and separation areas, wherein the separation areas are substantially free from light extraction features;
• and
• providing one or more solid-state light sources configured to be optically coupled to the at least one light input edge such that, when coupled to the at least one light input edge, light emitted from the one or more solid-state light sources is guided within the sheet and extracted by the two-dimensional pattern of light extraction features,
• wherein the two-dimensional pattern of light extraction features includes at least first, second, and third of the patterned areas located progressively farther from the at least one light input edge and separated from one another by one or more of the separation areas, and
• wherein an areal density of the first of the patterned areas is less than an areal density of the second of the patterned areas, and the areal density of the second of the patterned areas is less than an areal density of the third of the patterned areas.