Light guide with cladding layers

A light guide device has a core layer 2a with upper and lower cladding layers 6b, 7b, microlenses 8b and scattering structures 4. The refractive indices of the core layer and the microlenses are greater than the refractive index of the cladding layer. Each of the scattering structures 4 may have a microlens 8b above it. The refractive indices of the core layer and the microlenses may be substantially the same. The refractive indices of the core layer and the microlenses may be in the range 1.4 to 1.8. The refractive index of the cladding layers may be in the range 1.25 to 1.4. The microlenses may be Fresnel lenses and may be made from polycarbonate or a uv curing material. The device may be used as a backlight for a liquid crystal display (LCD).