Arc discharge lamp having polycrystalline ceramic arc tube

Claim 1

AN ELECTRIC ARC LAMP COMPRISING A BASE MEMBER HAVING A PLURALITY OF ELECTRICAL CONTACTS AND AN EXTERIOR LIGHT-TRANSMISSIVE ENVELOPE ATTACHED THERETO; A SECOND INNER LIGHT-TRANSMISSIVE ENVELOPE SUSPENDED WITHIN SAID FIRST ENVELOPE AND COMPRISING A TUBULAR LIGHT-TRANSMISSIVE POLYCRYSTALLINE REFRACTORY OXIDE BODY, A PAIR OF APERTURED END CAP MEMBERS OF THE SAME LIGHT-TRANSMISSIVE POLYCRYSTALLINE REFRACTORY OXIDE AS SAID TUBULAR BODY CLOSING OPPOSITE ENDS OF SAID BODY AND HERMETICALLY SEALED THERETO, AT LEAST A PAIR OF ARC-ELECTRODES CONTAINED WITHIN SAID INNER ENVELOPE AND MOUNTED ON SUPPORT RODS WHICH ARE HERMETICALLY SEALED THROUGH SAID END CAPS TO PROVIDE A HERMETICALLY SEALED ENVELOPE, AND A CHARGE OF A STARTING GAS AND A VAPORIZABLE LIGHT-EMITTING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF ACTIVE METALS AND ACTIVE METAL HALIDES WITHIN SAID ENVELOPE; AND MEANS FOR MECHANICALLY SUPPORTING SAID INNER ENVELOPE WITHIN SAID OUTER ENVELOPE AND FOR ELECTRICALLY CONNECTING SAID ARC-ELECTRODES TO RESPECTIVE CONTACTS ON SAID BASE MEMBER.