Patent ID: 8840746

Claim:
A method, comprising: manufacturing an apparatus comprising a first sheet and a light source disposed near an edge of the first sheet comprising, manufacturing a first sheet comprising particles, from a second sheet and a third sheet, the concentration of particles in the first sheet being uniform through the entire thickness direction of the first sheet at any location on the first sheet and the concentration of particles continuously varying across the entire width and/or the entire length of the first sheet; providing the second sheet having a second concentration of particles and a first shape with varying thickness, providing the third sheet having a third concentration of particles and a second shape with varying thickness, and merging the second sheet and the third sheet along curved surfaces of the second sheet and the third sheet to generate the first sheet; wherein the second sheet is merged to the third sheet by fusion, which comprises physical diffusion of the particles from the second sheet into the third sheet; the physical diffusion is strong enough to cause a local homogenization of the concentration of the particles of the first sheet without causing the homogenization of the concentration of the particles over the whole of the first sheet; and the local homogenization comprises homogenization spanning the thickness of the first sheet.