A photoelectric module (1) comprises an electrically non-conducting support (2) and a photoelectric element including an array of spatially distributed photoelectric members applied to a surface of the support (2). High simplicity and efficiency is obtained by the double function of module (1) for light transmission or reflection, and spatially averaged light measurement. In a preferred application of module (1) a light source (8, LED) is energized by a driving circuit (9) controlled by an electronic circuit (11). The input of this circuit (11) is connected to the photoelectric module (1), the power delivered to the light source (8) and the intensity of the light beam emitted by the light source being regulated preferably to a constant value by the feedback loop consisting of module (1), electronic circuit (11) and driving circuit (9).