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he said, but the tinting makes it look like the original glass,
only more lightweight. Now, most of the weight comes from
The concentric graduation that characterize Fresnel
lenses can be particularly difficult to replicate. Historically,
they were so precise that the central lens, which has a
series of concentric rings around it, all pressed together
like a slip fit with some glue in between. Spinella said that
it would be possible to do now, but it would take a much
longer time than it takes to make the lens out of a single,
perforated piece. It’s also less expensive and easier to
make them that way.
In their case study, Star Prototype said they needed to
take particular care in the speed and feed of the cutter
head, since the finish quality had to be as high as possible
in order to produce a working lens.
“To produce the high level of visual quality needed
for this type of lighthouse lens project, it requires a
combination of the latest cutting-edge 3D technologies
and traditional craftsmanship,” said
Trevor Thompson, the U.S. southeast coast technical
sales engineer for Star Prototype. “Star Prototype provides
just the right combination of 3D machining capabilities
and highly trained staff, with traditional hand polishing and
Another challenge Star Prototype had to deal with was
the size of the prisms, which can be four inches thick.
“The beautiful challenge on this project was, for us,
the need to combine precise machining services with an
equally high level of hand craftsmanship,” said Gordon
Styles, founder and president of Star Prototype. “Artworks
knew exactly what they wanted, and they raised the bar
pretty high to achieve a result that would pay respect to the
artisans who made the original lenses while using modern
materials. I think we took as much pleasure in making these
After the machining, the acrylic parts needed to be
buffed and polished by hand.
“Although this process is painstaking, it’s necessary to
make optical quality clear prisms that have sharply defined
corners and edges – something that would be impossible
to do with machine polishing alone,” Star Prototype wrote
in the case study.