A lighting apparatus for producing high brightness, said lighting apparatus comprising: a high thermal conductivity printed circuit board; at least one bare LED die comprising one or more LED emitting areas for generating radiation of one or more spectral bands over a predetermined solid angle, said at least one bare LED die being attached to said high thermal conductivity printed circuit board; an electronic control module for controlling the output of said LED emitting areas; a photosensor attached to said high thermal conductivity printed circuit board at a predetermined spaced apart location with respect to said LED die for providing a feedback signal to said electronic control module to regulate the output of said LED emitting areas; and at least one non-imaging concentrator fixedly attached to and in registration with said high thermal conductivity printed circuit board, said non-imaging concentrator having entrance and exit apertures (204, 110), said non-imaging concentrator entrance aperture being optically aligned with said LED emitting areas for collecting radiation from said LED emitting areas and re-emitting it through said non-imaging concentrator exit aperture with an étendue substantially the same as that of said LED emitting areas, the lighting apparatus being characterized in that: (a) said at least one bare LED die is attached to said high thermal conductivity printed circuit board with a thermally conductive bonding layer; (b) said electronic control module is attached to said high thermal conductivity printed circuit board; and (c) said non-imaging concentrator has prismatic optical elements (701, 703) positioned near said exit aperture for sampling the light emitted near said exit aperture and directing it by total internal reflection along a folded optical path to said photosensor as an optical signal indicative of the intensity of radiation exiting said non-imaging concentrator. a high thermal conductivity printed circuit board; at least one bare LED die comprising one or more LED emitting areas for generating radiation of one or more spectral bands over a predetermined solid angle, said at least one bare LED die being attached to said high thermal conductivity printed circuit board; an electronic control module for controlling the output of said LED emitting areas; a photosensor attached to said high thermal conductivity printed circuit board at a predetermined spaced apart location with respect to said LED die for providing a feedback signal to said electronic control module to regulate the output of said LED emitting areas; and at least one non-imaging concentrator fixedly attached to and in registration with said high thermal conductivity printed circuit board, said non-imaging concentrator having entrance and exit apertures (204, 110), said non-imaging concentrator entrance aperture being optically aligned with said LED emitting areas for collecting radiation from said LED emitting areas and re-emitting it through said non-imaging concentrator exit aperture with an étendue substantially the same as that of said LED emitting areas, (a) said at least one bare LED die is attached to said high thermal conductivity printed circuit board with a thermally conductive bonding layer; (b) said electronic control module is attached to said high thermal conductivity printed circuit board; and (c) said non-imaging concentrator has prismatic optical elements (701, 703) positioned near said exit aperture for sampling the light emitted near said exit aperture and directing it by total internal reflection along a folded optical path to said photosensor as an optical signal indicative of the intensity of radiation exiting said non-imaging concentrator.