Antireflective graded index silica coating, method for making

Patent · Tue Aug 13 04:00:00 EDT 1985

OSTI ID:6350202

Yoldas, B E; Partlow, D P

Antireflective silica coating for vitreous material is substantially non-reflecting over a wide band of radiations. This is achieved by providing the coating with a graded degree of porosity which grades the index of refraction between that of air and the vitreous material of the substrate. To prepare the coating, there is first prepared a silicon-alkoxide-based coating solution of particular polymer structure produced by a controlled proportion of water to alkoxide and a controlled concentration of alkoxide to solution, along with a small amount of catalyst. The primary solvent is alcohol and the solution is polymerized and hydrolized under controlled conditions prior to use. The prepared solution is applied as a film to the vitreous substrate and rapidly dried. It is thereafter heated under controlled conditions to volatilize the hydroxyl radicals and organics therefrom and then to produce a suitable pore morphology in the residual porous silica layer. The silica layer is then etched in order to enlarge the pores in a graded fashion, with the largest of the pores remaining being sufficiently small that radiations to be passed through the substrate are not significantly scattered. For use with quartz substrates, extremely durable coatings which display only 0.1% reflectivity have been prepared.

• Assignee: The United States of America as represented by the United States Department of Energy
• Patent Number(s): US 4535026
• OSTI ID: 6350202
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
ANTIREFLECTION COATINGS
CATALYSIS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COATINGS
CRYSTAL STRUCTURE
DECOMPOSITION
ETCHING
FABRICATION
GLASS
HYDROLYSIS
HYDROXYL RADICALS
LYSIS
MATTER
MICROSTRUCTURE
MINERALS
OPTICAL PROPERTIES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLYMERS
POROSITY
QUARTZ
RADICALS
REFLECTIVITY
REFRACTION
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOLVOLYSIS
SURFACE FINISHING
SURFACE PROPERTIES
SYNTHESIS
VOLATILE MATTER