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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

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 combined radiant energy. Sources of radiant energy of different wavelengths, typically different-color LEDs, supply radiant energy into the interior of the integrating cavity. In the examples, the points of entry of the energy into the cavity typically are located so that they are not directly visible through the aperture. The cavity effectively integrates the energy of different wavelengths, so that the combined radiant energy emitted through the aperture includes the radiant energy of the various wavelengths. The apparatus also includes a control circuit coupled to the sources for establishing output intensity of radiant energy of each of the sources. Control of the intensity of emission of the sources sets the amount of each wavelength of energy in the combined output and thus determines a spectral characteristic of the radiant energy output through the aperture.

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1. A lighting system comprising: a lighting fixture for a visible illuminating type lighting application in a region or area intended to be occupied by a person, the lighting fixture comprising:an optical integrating cavity having at least one white diffusely reflective interior surface and an optic

1. A lighting system comprising: a lighting fixture for a visible illuminating type lighting application in a region or area intended to be occupied by a person, the lighting fixture comprising:an optical integrating cavity having at least one white diffusely reflective interior surface and an optical passage for allowing emission of optically integrated light out of the cavity; anda plurality of light emitting diode (LED) sources coupled to directly supply light to the optical integrating cavity in one or more directions to cause substantial portions of light supplied by the sources to reflect from said at least one diffusely reflective surface of the optical integrating cavity one or more times to optically integrate the light from the sources before emission as the optically integrated light through the optical passage of the integrating cavity for the visible illuminating type lighting application;a control circuit coupled to the sources for establishing output intensity of light of each of the sources; anda deflector having a reflective inner surface coupled to the optical passage and configured to expand outward as it extends away from the optical passage for deflecting at least some of the optically integrated light emitted through the optical passage and defining a field of illumination for the emitted light with respect to the lighting application. 2. A lighting system comprising: a lighting fixture, configured as a downlight for a visible illuminating type lighting application in a region or area intended to be occupied by a person, the lighting fixture comprising:an optical integrating cavity having at least one white diffusely reflective interior surface and an optical passage for allowing emission of optically integrated light out of the cavity;a plurality of light emitting diode (LED) sources coupled to directly supply light to the optical integrating cavity in one or more directions to cause substantial portions of light supplied by the sources to reflect from said at least one diffusely reflective surface of the optical integrating cavity one or more times to optically integrate the light from the sources before emission as the optically integrated light through the optical passage of the integrating cavity for the visible illuminating type lighting application;a control circuit coupled to the sources for establishing output intensity of light of each of the sources; anda deflector having a reflective inner surface coupled to the optical passage and configured to expand outward as it extends away from the optical passage for deflecting at least some of the optically integrated light emitted through the optical passage and defining a field of illumination for the emitted light with respect to the lighting application. 3. The system of claim 2, wherein the LED sources provide sufficient light energy for the optically integrated light emitted through the optical passage to have a level sufficient for a task lighting or object illumination application. 4. A lighting system comprising: a lighting fixture for a visible illuminating type lighting application in a region or area intended to be occupied by a person, the lighting fixture comprising;an optical integrating cavity having at least one white diffusely reflective interior surface and an optical passage for allowing emission of optically integrated light out of the cavity; anda plurality of light emitting diode (LED) sources coupled to directly supply light to the optical integrating cavity in one or more directions to cause substantial portions of light supplied by the sources to reflect from said at least one diffusely reflective surface of the optical integrating cavity one or more times to optically integrate the light from the sources before emission as the optically integrated light through the optical passage of the integrating cavity for the visible illuminating type lighting application;a control circuit coupled to the sources for establishing output intensity of light of each of the sources; anda deflector having a reflective inner surface coupled to the optical passage and configured to expand outward as it extends away from the optical passage for deflecting at least some of the optically integrated light emitted through the optical passage and defining a field of illumination for the emitted light with respect to the lighting application,wherein light from the LED sources enters the optical integrating cavity at points on an interior surface of the optical integrating cavity, and the LED sources are not directly visible through the optical passage. 5. The lighting system of claim 1, wherein: at least two of the LED sources emit light of respective different colors, and the optical integrating cavity is configured to direct optically integrated light including light of the different colors through the optical passage in a direction to facilitate said visible illuminating type lighting application, andthe control circuit sets contributions of the different colors to the optically integrated light within the cavity and thus sets a spectral characteristic of the optically integrated light emitted through the optical passage of the optical integrating cavity. 6. The lighting system of claim 5, further comprising: a sensor responsive to the optically integrated light, wherein the control circuit maintains the spectral characteristic of the optically integrated light responsive to an output from the sensor. 7. The lighting system of claim 6, wherein the sensor comprises a color sensor for sensing a color characteristic of the optically integrated light in the optical integrating cavity. 8. The lighting system of claim 6, wherein the sensor comprises a light intensity sensor for sensing intensity of light in the optical integrating cavity. 9. A lighting system comprising: a lighting fixture for a visible illuminating type lighting application in a region or area intended to be occupied by a person, the lighting fixture comprising:an optical integrating cavity having at least one white diffusely reflective interior surface and an optical passage for allowing emission of optically integrated light out of the cavity; anda plurality of light emitting diode (LED) sources coupled to directly supply light to the optical integrating cavity in one or more directions to cause substantial portions of light supplied by the sources to reflect from said at least one diffusely reflective surface of the optical integrating cavity one or more times to optically integrate the light from the sources before emission as the optically integrated light through the optical passage of the integrating cavity for the visible illuminating type lighting application;a temperature sensor for sensing temperature during operation of the plurality of LED sources;a control circuit coupled to the sources for establishing output intensity of light of each of the sources; anda deflector having a reflective inner surface coupled to the optical passage and configured to expand outward as it extends away from the optical passage for deflecting at least some of the optically integrated light emitted through the optical passage and defining a field of illumination for the emitted light with respect to the lighting application. 10. The lighting system of claim 9, wherein the control circuit is at least partially responsive to an output of the temperature sensor. 11. The lighting system of claim 1, wherein the LED sources are mounted on a plate to emit light directly toward the diffusely reflective surface of the cavity. 12. The lighting system of claim 11, wherein the plate is rectangular. 13. The lighting system of claim 11, wherein the plate is thermally conductive to wick away heat from the LED sources. 14. The lighting system of claim 11, wherein the plate is at least substantially circular and includes an aperture. 15. The lighting system of claim 11, wherein the cavity is at least substantially hemispherical. 16. The lighting fixture of claim 15, the cavity is at least substantially semicylindrical.