Patent ID: 7300175

Claim:
White light illumination apparatus, said apparatus comprising: at least one LED having an output in the blue region of the spectrum; at least one other LED having an output in the red region of the spectrum; a reflector positioned upstream of said of LEDs to intercept radiation emitted upstream of said LEDs and redirect it downstream where in can be used at least in part to contribute to the white light output of said illumination apparatus; a phosphor layer having entrance and exit surfaces, said phosphor layer being configured and arranged to intercept the outputs from said LEDs via its entrance surface, partially absorb blue light and convert it to yellow light, and transmit the unabsorbed blue light, along with the yellow and red light, to form a combined output of white light at its exit surface, said white light emerging from said phosphor layer exit surface over a predetermined solid angle; an optical band pass filter positioned intermediate said LEDs and said phosphor layer for selectively controlling the spectral content of radiation traveling downstream to said phosphor layer and back upstream to said LEDs; and a non-imaging concentrator for collecting substantially all of the white light transmitted by said phosphor layer and emitting it as a beam having a diverging solid angle smaller than said predetermined solid angle of said exit surface, said non-imaging concentrator having an entrance aperture for receiving the white light emerging from the exit surface of said phosphor layer and an exit aperture from which said white light emerges spatially and spectrally uniform in the near field of said exit aperture.