An optical surface substrate. The optical substrate features a three-dimensional surface. The optical substrate is defined by a first surface structure function modulated by a second surface structure function, the first surface structure function producing at least one specular component from a first input beam of light. The second surface structure function has a geometry with at least pseudo-random characteristics to modulate the first surface structure function such that the surface of the optical substrate produces specular and diffuse light from the first input beam of light. The optical substrate is suitable for use in a variety of applications, including brightness enhancement and projection devices.