A system to provide radiant energy of selectable spectral characteristic (e.g. a selectable color combination) uses an integrating cavity to combine energy of different wavelengths from different sources. The cavity has a diffusely reflective interior surface and an aperture for allowing emission of...http://www.google.com/patents/US7157694?utm_source=gb-gplus-sharePatent US7157694 - Integrating chamber cone light using LED sources
