Antireflective graded index silica coating, method for making
- Churchill, PA
- Wilkinsburg, PA
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.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- DOE Contract Number:
- AC04-76
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 4535026
- OSTI ID:
- 865551
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
graded
index
silica
coating
method
vitreous
material
substantially
non-reflecting
wide
band
radiations
achieved
providing
degree
porosity
grades
refraction
air
substrate
prepare
prepared
silicon-alkoxide-based
solution
particular
polymer
structure
produced
controlled
proportion
water
alkoxide
concentration
amount
catalyst
primary
solvent
alcohol
polymerized
hydrolized
conditions
prior
applied
film
rapidly
dried
thereafter
heated
volatilize
hydroxyl
radicals
organics
therefrom
produce
suitable
pore
morphology
residual
porous
layer
etched
enlarge
pores
fashion
largest
remaining
sufficiently
passed
significantly
scattered
quartz
substrates
extremely
durable
coatings
display
reflectivity
wide band
porous silica
controlled conditions
thereafter heated
silica coating
graded index
durable coatings
hydroxyl radicals
polymer structure
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