Abstract: The invention relates to a triple prism which reflects light, a reflector and to a method for recognizing an object. A reflective photoelectric barrier sends light to a reflector. The reflector does not answer with the form of the obtained light signal, but with a double signal which projects two light centers. The reflector can also be embodied such that it answers with a different geometric figure than the light projection. The reflector with a modified signal enables a sensor system to be produced and which can verify, by evaluating the light signal captured by the reflector, whether the captured signal of the reflector or another reflection.