Abstract: A light guide module (4) and backlight that incorporates this module are disclosed. In some embodiments, a light guide module includes a light guide (1) having an input surface (11) to receive light. The module also includes a structured surface layer (2) including a first surface (812) and a second surface (13). The first surface (12) is attached to the input surface (11) of the light guide (1). And the second surface (13) includes microstructures (21) that are operable to spread incident light in the plane of the light guide (1). The second surface (13) is positioned to receive light emitted from an array of light emitting diodes (3).