Scintillator structures are disclosed in which the phosphor is embedded or suspended in an optically transparent matrix which is selected or adjusted to have an index of refraction which is approximately equal to that of the phosphor embedded therein at the wavelength of the light emitted by the phosphor....http://www.google.com.au/patents/US4375423?utm_source=gb-gplus-sharePatent US4375423 - Index-matched phosphor scintillator structures
