Abstract:
An electric lamp, such as an incandescent linear quartz heat lamp, is provided having a vitreous light transmissive envelope having an exterior surface and a light source capable of generating light within said envelope. Disposed on a portion of the exterior surface of the envelope is a diffuse reflective coating, such as a boron nitride coating, for reflecting at least a portion of the light emitted by the source. A protective silica coating encapsulates the reflective coating to protect the reflective coating from things such as abrasion, moisture, and cleaning solvents.
Abstract:
A reflector, e.g. an all glass reflector (10) having a front reflecting surface and terminating in the rear in a cavity (14) into which a lamp is cemented transmits substantially less light out of the rear when at least the inside or the outside of the cavity and the reflecting surface are coated with an optical interference coating (24). The coating is preferably applied by a low pressure chemical vapor deposition process.
Abstract:
Incandescent lamps or arc lamps having an infrared red reflecting multilayer optical interference filter on the outer surface of the vitreous or fused quartz lamp envelope enclosing the filament have a light-scattering coating applied over the filter to scatter light emitted by the lamp and thereby diffuse the filament image. The light-scattering coating consists of light-scattering particles, such as alumina, dispersed in a silica matrix. This coating is formed by applying to the filter a silicone solution in which is dispersed colloidal silica and light-scattering particles and pyrolyzing at high temperature to drive off the organic components and form the silica matrix.
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 (cracking, peeling) 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 glas 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 ranging from about 550 to about 800°C and holding same within that temperature range for at least about one hour.
Abstract:
Thin film interference filters consisting of alternating layers of tantala and silica suitable for high temperature use on electric lamps have been made by heat treating at 550-675°C before using the filters at high temperature. Tungsten halogen lamps made with such heat treated filters have been thermally cycled for thousands of cycles at 900°C with no film loss and with satisfactory optical performance.
Abstract:
Thin film interference filters consisting of alternating layers of tantala and silica suitable for high temperature use on electric lamps have been made by heat treating at 550-675°C before using the filters at high temperature. Tungsten halogen lamps made with such heat treated filters have been thermally cycled for thousands of cycles at 900°C with no film loss and with satisfactory optical performance.
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 ranging from about 550 to about 800°C and holding same within that temperature range for at least about one hour.