Infrared conservation in SOX lamps

This picture shows the importance of the outer jacket in the operation of the low-pressure sodium burner. This jacket is internally coated with a thin layer of indium-tin oxide, a semi-conductor material characterized by a high charge density and mobility enabling a high reflectivity of infrared radiation. This characteristic is instrumental in limiting heat losses from the burner, which is critical to the realization of a high lumen efficacy.