| 摘要 |
Disclosed is an optical element (10) comprising a central cavity (20) extending from a first aperture (12) to a second aperture (14) of the optical element, said central cavity gradually widening in a direction from the first aperture to the second aperture, said central cavity being delimited by a stack of transparent frustums (30) including a first frustum defining the first aperture and a final frustum defining the second aperture, each frustum having a prismatic outer surface (32) having a first surface portion (34) tapering in the direction from the second aperture to the first aperture and a continuous inner surface (36), wherein the respective continuous inner surfaces combine to delimit said central cavity. Also disclosed is a lighting device including such an optical element and a luminaire including such a lighting device. |
