Antireflective graded index silica coating, method for making

Patent · Tue Jan 01 04:00:00 EST 1985

OSTI ID:865551

Yoldas, Bulent E ^[1]; Partlow, Deborah P ^[2]

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1. Churchill, PA
2. 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
• 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

Related Subjects

/428/216/359/427/
achieved
air
alcohol
alkoxide
amount
antireflective
applied
band
catalyst
coating
coatings
concentration
conditions
controlled
controlled conditions
degree
display
dried
durable
durable coatings
enlarge
etched
extremely
fashion
film
graded
graded index
grades
heated
hydrolized
hydroxyl
hydroxyl radicals
index
largest
layer
material
method
morphology
non-reflecting
organics
particular
passed
polymer
polymer structure
polymerized
pore
pores
porosity
porous
porous silica
prepare
prepared
primary
prior
produce
produced
proportion
providing
quartz
radiations
radicals
rapidly
reflectivity
refraction
remaining
residual
scattered
significantly
silica
silica coating
silicon-alkoxide-based
solution
solvent
structure
substantially
substrate
substrates
sufficiently
suitable
thereafter
thereafter heated
therefrom
vitreous
volatilize
water
wide
wide band