A light pipe includes a surface provided with a pattern that has
diffractive properties, where the pattern has uniform, mutually different
areas on the surface such that some of the areas are configured to
distribute light from a light input end of the light pipe to form
macroscopically uniform distribution of light and some other areas are
configured to couple light out from the light pipe in order to produce
lighting, and where the relative proportion of surface covered by areas
configured to distribute light is arranged to decrease in relation to
increase of distance from the light input end.