Method for making a tantala/silica interference filter on a vitreous substrate and an electric lamp made thereby

摘要

A method for making a tantala/silica interference filter on a vitreous substrate, the filter retaining integrity at temperatures in excess of 600 DEG C, includes the steps of applying to the vitreous substrate a first coating of vitreous silica doped with submicron-sized particles, depositing on the first coating by low pressure chemical vapor deposition the filter which comprises a second coating comprising alternating layers of tantala and silica, and heat treating the substrate and first and second coatings to bond the filter to the substrate. There is further provided an electric lamp having an envelope made in accordance with the above method. <IMAGE>