US Patent 7942537 Light-emitting device with brightness enhancing layer

A brightness enhancing means (5), comprising a collimating means (6) having a receiving area (61), an output area (62) being larger than said receiving area (61), and sidewalls (63) at least partially extending between said receiving and output areas, is provided. At least a portion of the sidewalls (63) of said collimating means (6) comprises a first filter being arranged to reflect light of a first light property, which light is received via said receiving area (61) of said first collimating means (6), towards said output area (62) of said first collimating means (6), wherein said first filter is a dichroic filter or a polarization filter.