High purity fused silica with low absolute refractive index
AssigneeCorning Incorporated
InventorsCarlos Duran, Richard Michael Fiacco, Kenneth Edward Hrdina, Daniel Raymond Sempolinski
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Abstract
A fused silica glass article having a low absolute refractive index and low concentrations of hydroxyl groups, halogens, and metal having a low absolute refractive index. The glass article contains less than about 10 ppm protium-containing and deuterium-containing hydroxyl groups by weight and less than about 20 ppm halogens by weight. The silica glass article also has an absolute refractive index (ARI) less than or equal to 1.560820. In one embodiment, the ARI of the fused silica article is achieved by lowering the fictive temperature of the fused silica. A method of lowering the fictive temperature is also described.
Claims15
A fused silica article, the fused silica article having a combined concentration of protium-containing hydroxyl groups and deuteroxyl groups of less than about 10 ppm, wherein the fused silica article has an absolute refractive index of less than or equal to 1.560820 at a wavelength of 193.368 nm, and wherein the fused silica article has a fictive temperature of less than 1050° C.
A fused silica article, the fused silica article having fictive temperature of less than 1050° C. and an anneal point of at least 1200° C., wherein the fused silica article has an absolute refractive index has an absolute refractive index of less than or equal to 1.560820 at a wavelength of 193.368 nm.
A method of annealing a fused silica glass, the method comprising the steps of:
- a. providing a fused silica glass, the fused silica glass having an anneal point, an anneal rate, a strain point, and a fictive temperature;
- b. heating to a first temperature above the anneal point;
- c. cooling the fused silica glass to a second temperature below the strain point at a progressively decreasing cooling rate, wherein the progressively decreasing cooling rate is less than the anneal rate of the fused silica glass;
- and
- d. cooling the fused silica glass from the second temperature to room temperature at a third cooling rate, thereby annealing the fused silica glass, wherein the annealed fused silica glass has an absolute refractive index of less than or equal to 1.560820 at a wavelength of 193.368 nm and a fictive temperature of less than 1050° C.
Dependencies are inferred from the claim text.