Self-calibrating optical probe heads for the scanning of supply meters. Existing energy meters that do not have a pulse output can be included in the energy management at low cost and with no conversion required. Furthermore, the energyproportional pulses of electronic meters can be registered. Suitable for various fields of application, e.g. industrial systems, large houses with several flats, shopping centres,trade fairs and exhibitions, holiday and camping resorts, hotel and apartment installations, municipalities and authorities.