An apparatus for providing a light output to an optical guide for illumination of an imaged object, the apparatus comprising: a plurality of LED light sources each of which are independently powered and independently controlled, each light source emitting light at a wavelength which is different from the wavelength emitted by the other light sources; a heat sink configured to thermally couple the plurality of LED light sources and provide conduction of heat generated by the plurality of light sources; optical elements (222, 224, 226) to collect, collimate, and combine the emissions from the plurality of light sources into a combined beam of light to be optically coupled to the light guide; wherein the light sources are arranged on the heat sink in thermal contact with a single heat spreader plate on a plane which is common to a planar surface of the heat sink on the single heat spreader plate; wherein all optical elements not directly attached to the LED light sources are mounted in a mechanical enclosure, the enclosure having a linear array of input ports matching a linear pattern of the light sources on the heat spreader plate and a single output port sealable by a shutter in the absence of a light guide; the heat spreader plate with the light sources being assembled to the enclosure input ports so as to seal the enclosure, characterized in that dichroic filters (244, 246, 248) are configured to couple the collimated emission from each of the plurality of LED light sources into the combined beam of light directed along a common path to an output port, wherein the relative optical path length associated with each one of the plurality of LED light sources is based on the relative difference in wavelength, with the optical path length increasing with wavelength. a plurality of LED light sources each of which are independently powered and independently controlled, each light source emitting light at a wavelength which is different from the wavelength emitted by the other light sources; a heat sink configured to thermally couple the plurality of LED light sources and provide conduction of heat generated by the plurality of light sources; optical elements (222, 224, 226) to collect, collimate, and combine the emissions from the plurality of light sources into a combined beam of light to be optically coupled to the light guide; wherein the light sources are arranged on the heat sink in thermal contact with a single heat spreader plate on a plane which is common to a planar surface of the heat sink on the single heat spreader plate; wherein all optical elements not directly attached to the LED light sources are mounted in a mechanical enclosure, the enclosure having a linear array of input ports matching a linear pattern of the light sources on the heat spreader plate and a single output port sealable by a shutter in the absence of a light guide; the heat spreader plate with the light sources being assembled to the enclosure input ports so as to seal the enclosure, characterized in that dichroic filters (244, 246, 248) are configured to couple the collimated emission from each of the plurality of LED light sources into the combined beam of light directed along a common path to an output port, wherein the relative optical path length associated with each one of the plurality of LED light sources is based on the relative difference in wavelength, with the optical path length increasing with wavelength.