| 摘要 |
PROBLEM TO BE SOLVED: To provide a tantalum/silica interference filter that is on a vitreous substrate and holds its deposition completeness at >=600 deg.C, by forming tantalum/ silica coatings on a substrate in two steps by the low-pressure chemical vapor deposition method. SOLUTION: A first tantalum/silica coating 18 is deposited on one surface 16 of a vitreous substrate, typically a light-transmittable vitreous envelope 12 for an electric lamp 10, by low-pressure chemical vapor deposition method. On the first coating 18, a second tantalum/silica coating 24 is deposited by the low-pressure chemical vapor deposition method. The first and second coatings 18 and 24 should have total thicknesses at least 3.5μm. The first and second coatings 18 and 24 are made of alternated layers of tantalum 20 and silica 22. After its application, the first coating 18 is preferably heat-treated at temperatures from 550 deg.C to 675 deg.C for 0.5 to 5.0 hrs.
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