Effects of Volume Scattering Diffusers on the Color Variation of White Light LEDs

This study analyzed the variation of the correlated color temperature (CCT) of white light, which was emitted from Lambertian-type LEDs, and passed through a volume scattering diffuser (VSD). The tested VSD, fabricated by mixing scattering particles (PMMA) in glue (epoxy), exhibited various concentration weights of the scattering particles. Measurements showed that the CCT values decreased and the CCT variations exhibited oscillatory behavior, as the concentration of scattering particles increased. Furthermore, the results regarding CCT variation demonstrated that a higher CCT source is more sensitive to the concentration than a lower CCT source is, suggesting that the power loss of shorter-wavelength light is greater than that of longer-wavelength light, when the light passes through a VSD.