(EP898583-A1)      Preparing a fluorescent dyed polymer compsn. comprises dissolving by means of ultrasonic agitation a fluorescent dye in a soln. of mono(methyl methacrylate) or partially polymerised methyl methacrylate, and adding either before, during or after dissolution organic peroxide initiator at a sufficient temp. to initiate the polymerisation and produce the fluorescent dyed polymer compsn. without the formation of voids or bubbles. Also claimed is a fluorescent dyed polymer compsn. prepd. as above, and a luminescent sunlight collector comprising the fluorescent dyed polymer compsn..    USE -   Used for making luminescent sunlight collectors for illumination of buildings and as fluorescent concentrators for solar cells.    ADVANTAGE -   The problem with prior fluorescent dyes was that they suffered from light emission losses through various mechanisms, such as absorption and scattering in dyed polymer. A means has been achieved of increasing the half-length of the fluorescent dyed polymer so as to increase the distance over which the fluorescently emitted light can travel within any length of a sunlight collector.    (JP2000504356-W)      Preparing a fluorescent dyed polymer compsn. comprises dissolving by means of ultrasonic agitation a fluorescent dye in a soln. of mono(methyl methacrylate) or partially polymerised methyl methacrylate, and adding either before, during or after dissolution organic peroxide initiator at a sufficient temp. to initiate the polymerisation and produce the fluorescent dyed polymer compsn. without the formation of voids or bubbles. Also claimed is a fluorescent dyed polymer compsn. prepd. as above, and a luminescent sunlight collector comprising the fluorescent dyed polymer compsn..    USE -   Used for making luminescent sunlight collectors for illumination of buildings and as fluorescent concentrators for solar cells.    ADVANTAGE -   The problem with prior fluorescent dyes was that they suffered from light emission losses through various mechanisms, such as absorption and scattering in dyed polymer. A means has been achieved of increasing the half-length of the fluorescent dyed polymer so as to increase the distance over which the fluorescently emitted light can travel within any length of a sunlight collector.