Measured luminance and visual appearance of multi-color persistent phosphors.
In the past decade, several persistent phosphors were intensively studied, such as CaAl(2)O(4):Eu,Nd (blue) and SrAl(2)O(4):Eu,Dy (green). Yellow-to-red emitting persistent phosphors have also been identified. All these phosphors are normally evaluated by measuring their afterglow as a function of time in photometric units. However, the eye sensitivity curve shifts from photopic vision to scotopic vision upon decreasing light intensity, with a corresponding decrease in red-sensitivity. Performance of red-emitting persistent phosphors thus cannot be described with usual photometry. An alternative description is presented, based on recent vision research in the intermediate (mesopic) region and using a unified system of photometry. It turns out that this effect seriously compromises the development of red-emitting persistent phosphors. This is illustrated on a number of commercially available persistent phosphors.
Poelman
Dirk
D
Department of Solid State Sciences, LumiLab, Ghent University, Gent, Belgium. dirk.poelman@ugent.be
Avci
Nursen
N
Smet
Philippe F
PF
D003116:Color; D003118:Color Perception / Q000502:physiology*; D055253:Color Vision / Q000502:physiology*; D003624:Darkness; D006801:Humans; D008027:Light; D008029:Lighting; D055254:Night Vision / Q000502:physiology; D010753:Phosphoranes; D010783:Photometry / Q000379:methods; D012160:Retina / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology; D014961:X-Ray Diffraction
D010753:Phosphoranes