9 EQUIPMENT UTILIZED IN OPTICAL COMMUNICATIONS SYSTEMS, NAMELY MODULATORS FOR CONVERTING VIDEO AND AUDIO INPUT SIGNALS TO AN FM OUTPUT; REPEATERS AND TRANSCEIVERS FOR CONVERTING OPTICAL SIGNALS TO ELECTRICAL FORM, AMPLIFYING, AND RECONVERTING TO OPTICAL FOR TRANSMISSION; OPTICAL RECEIVERS FOR CONVERTING OPTICAL SIGNALS INTO ELECTRICAL SIGNALS; AND TRANSMITTERS FOR CONVERTING ELECTRICAL SIGNALS TO INTENSITY MODULATED OPTICAL SIGNALS