Lighting installation with peripheral lighting source

摘要

An edge lit illumination device is described. The device has at least one light source and a light transmission element having at least one light output surface and at least one light ingress edge substantially perpendicular to said surface. The light source is located adjacent to the light ingress edge so that light from the light source enters the transmission element via the said edge and propagates through the element. The light output surface is uniformly roughened across the output surface. The roughening is sufficiently fine to give an average Ra value across the surface of less than 1.0 mum/mm thickness of the element or drop-off of light output across the surface of less than 5000 lux.