Tantala-silica interference filters and lamps using same
US5422534A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 1992 |
| Grant date | Jun 6, 1995 |
| Priority date | — |
| Expiry date | Nov 18, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01K3/005
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An optical interference filter produced on a vitreous, light transmissive substrate, such as an electric lamp envelope, includes a plurality of alternating layers of tantala and silica in which each tantala layer includes titania in an amount of less than about 10 mole % whereby the microstructure of the tantala layers is controlled during subsequent crystallization and extrinsic stress in the tantala layers is reduced. Rather than or in addition to including titania in each tantala layer, the present invention additionally contemplates placing at least some of the tantala layers in contact with a titania layer (pre-layer and/or post-layer) whereby the microstructure of the tantala layers is controlled during subsequent crystallization and extrinsic stress in the tantala layers is reduced. The optical interference filters are produced by a process comprising depositing a plurality of alternating layers of tantala and silica on a vitreous, light transmissive substrate from respective precursors thereof by CVD, preferably LPCVD, to form a coated substrate. The filter may then be heated for a time and to a temperature effective to crystallize the tantala, preferably to a temperature r…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.