Abstract: A system provides white light having a selectable spectral characteristic (e.g. a selectable color temperature) using an optical integrating cavity to combine energy of different wavelengths from different sources with white light. The cavity has a diffusely reflective interior surface and an aperture for allowing emission of combined light. Control of the intensity of emission of the sources sets the amount of primary color light of each wavelength added to the substantially white input light output and thus determines a spectral characteristic of the white light output through the aperture. A variety of different elements may optically process the combined light output, such a deflector, a variable iris, a lens, a variable focusing lens system, a collimator, a holographic diffuser and combinations thereof.

Abstract: A desired color of illumination of a subject is achieved by determining settings for color inputs and applying those setting to one or more systems that generate and mix colors of light, so as to provide combined light of the desired character. In the examples of appropriate systems, an optical integrating cavity diffusely reflects light of three or more colors, and combined light emerging from an aperture of the cavity illuminates the subject. System settings for amounts of the different colors of the input lights are easily recorded for reuse or for transfer and use in other systems.