INCANDESCENT LAMP HAVING HARDGLASS ENVELOPE WITH INTERFERENCE FILTER

摘要

An incandescent lamp having an envelope of hardglass. The envelope encloses a tungsten filament and contains a fill material including an inert fill gas and a halogen additive. An interference filter for selectively reflecting and transmitting selected portions of the light spectrum emitted by the filament is disposed on the envelope. A barrier coating of silicon dioxide is preferably disposed on a substantial portion of the internal surface of the envelope. The barrier coating prevents the halogen additive from combining with alkaline ions of the hardglass envelope.