An illuminator for control lights used in traffic control, such as traffic lights, railway signal heads or line lights for waterborne traffic, in which illuminator the light source consists of one or more LEDs (2) fitted in lens holders (3) by means of which they can be connected onto a connection base (1) and which illuminator comprises optical feedback wherein one or more light-sensitive detectors (4) are arranged on the connection base (1) in connection with the LEDs used as light sources, some of the light coming from the LEDs being conveyed to said detectors, by means of which an optical feedback is formed for monitoring and/or adjusting the operation of the illuminator. The lens holders (3) are at least partly permeable to light so that light emitted laterally from the LEDs can be conveyed to the light-sensitive detectors fitted on the connection base.