9 ELECTRICAL APPARATUS AND INSTRUMENTS NAMELY, DISTRIBUTED TEMPERATURE SYSTEMS UTILIZING FIBER OPTIC CABLE FOR MEASURING, COLLECTING, RECORDING, STORING, TRANSMITTING AND REPRODUCING TEMPERATURE AND OTHER DATA IN REMOTE OR DEEP LOCATIONS; DISTRIBUTED TEMPERATURE SYSTEMS UTILIZING FIBER OPTIC CABLE FOR MEASURING, COLLECTING, RECORDING, STORING, TRANSMITTING AND REPRODUCING TEMPERATURE AND OTHER DATA IN THE FIELD OF THE GAS, OIL AND MINERAL EXTRACTION INDUSTRIES; OPTICAL APPARATUS AND INSTRUMENTS; NAMELY LASER SOURCES, SIGNAL PROCESSOR AND COUPLERS; FIBER OPTIC CABLE; SENSORS, NAMELY, FIBER OPTIC SENSORS; TRANSMITTERS FOR LIGHT AND ELECTRICAL SIGNALS TO FIBER OPTIC CABLE; RECEIVERS FOR PROCESSING SIGNALS FROM FIBER OPTIC SENSORS