A FEEDBACK CONTROLLED ILLUMINATION SYSTEM HAVING AN ARRAY OF LEDS, AND A DETECTOR AMONG THE LEDS

摘要

The present invention relates to an illumination system (11) having an array of differently coloured LEDs (13) , a plurality of collimators (15) , wherein each collimator (15) holds at least one LED (13) , a light mixing element (17) , arranged to mix light generated by the LEDs (13) into a mixed light that is emitted from the illumination system (11) , and a control system for controlling the colour balance of the mixed light. The control system comprises a detector (19) , which is placed among said collimators (15) and1 encircled by a light shield. The detector (19) detects a fraction of the mixed light that is reflected at an exit window (23) of the mixing element (17) . In this structure the detected light twice passes the mixing element (17) , which provides for a proper mixing of the different colours as well as a proper homogenisation of the light.