an led light source produces a narrow beam of light having a linear field of illumination , which is substantially uniform across the linear field . the light source comprises at least one light emitting diode and preferably a plurality of leds , an optical element for the efficient collection of energy radiating from the led or leds , and an optical element for distributing the collected energy into the linear field of illumination . the apparatus also includes a device or heat sink for thermal management . one or more electronic control circuits are coupled to the led or leds to variably and selectively control them . when a plurality of leds are used , the colors produced by the leds may different so that the light source is collectively controllable to provide a range of optically mixed colors .