High rate deposition for the formation of high quality optical coatings

Abstract

High rate deposition methods comprise depositing a powder coating from a product flow. The product flow results from a chemical reaction within the flow. Some of the powder coatings consolidate under appropriate conditions into an optical coating. The substrate can have a first optical coating onto which the powder coating is placed. The resulting optical coating following consolidation can have a large index-of-refraction difference with the underlying first optical coating, high thickness and index-of-refraction uniformity across the substrate and high thickness and index-of-refraction uniformity between coatings formed on different substrates under equivalent conditions. In some embodiments, the deposition can result in a powder coating of at least about 100 nm in no more than about 30 minutes with a substrate having a surface area of at least about 25 square centimeters.

What we claim is: 
     
         1 . A method for forming an optical coating on a substrate having a first coating, the method comprising depositing a powder coating on the first coating from a product flow wherein the product flow results from a chemical reaction in the flow and wherein the powder coating consolidates under appropriate conditions into an optical coating wherein the optical coating and the first coating, following consolidation, have a difference in index-of-refraction of at least about 1%. 
     
     
         2 . The method of  claim 1  wherein the optical coating and the first coating, following consolidation, have a difference in index-of-refraction of at least about 1.5%. 
     
     
         3 . The method of  claim 1  wherein the optical coating and the first coating, following consolidation, have a difference in index-of-refraction of at least about 2%. 
     
     
         4 . The method of  claim 1  wherein the powder coating comprises a silica glass. 
     
     
         5 . The method of  claim 4  wherein the silica glass is doped with phosphorous. 
     
     
         6 . The method of  claim 4  wherein the silica glass is doped with germanium. 
     
     
         7 . The method of  claim 1  wherein the powder coating has an average primary particles size no more than about 500 nanometers. 
     
     
         8 . The method of  claim 1  wherein the powder coating has an average primary particles size no more than about 100 nanometers. 
     
     
         9 . The method of  claim 1  wherein the powder coating has effectively no primary particles with a diameter greater than about 10 times the average diameter. 
     
     
         10 . The method of  claim 1  wherein the first coating comprises a powder coating prior to consolidation. 
     
     
         11 . The method of  claim 1  wherein the first coating comprises a consolidated glass prior to consolidation. 
     
     
         12 . The method of  claim 1  wherein the chemical reaction is driven by energy from a radiation beam. 
     
     
         13 . The method of  claim 12  wherein the radiation beam is generated by a laser. 
     
     
         14 . The method of  claim 1  wherein the depositing is performed within a reaction chamber. 
     
     
         15 . The method of  claim 1  wherein the substrate has a surface area of at least about 25 square centimeters and wherein the method comprises depositing a powder coating onto the first coating from a product flow with a thickness of at least about 100 nm in no more than about 30 minutes. 
     
     
         16 . A method for forming an optical coating on a substrate, the method comprising depositing a powder coating on the substrate from a flow wherein the product flow results from a chemical reaction in the flow and wherein the powder coating consolidates into an optical coating comprising a silicate glass with at least about 20 weight percent germanium oxide (GeO 2 ). 
     
     
         17 . The method of  claim 16  wherein the optical coating comprises a silicate glass with at least about 25 weight percent germanium oxide (GeO 2 ). 
     
     
         18 . The method of  claim 16  wherein the optical coating comprises a silicate glass with from about 30 weight percent to about 35 weight percent germanium oxide (GeO 2 ). 
     
     
         19 . The method of  claim 16  wherein the powder coating comprises silica. 
     
     
         20 . The method of  claim 16  wherein the chemical reaction is driven by energy from a laser. 
     
     
         21 . The method of  claim 16  wherein the silicate glass further comprises from about 1 weight percent to about 5 weight percent B 2 O 3 . 
     
     
         22 . The method of  claim 16  wherein the substrate comprises a first coating and wherein the powder coating consolidates under appropriate conditions into an optical coating wherein the optical coating and the first coating, following consolidation, have a difference in index-of-refraction of at least about 1%.