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Brief
An anti-reflection coating was needed to maximise
light transmission from the 'Cyclops' headlight
of the BMW / Williams Le-Mans 24 hour race car.
The coating had to operate at 25 - 40 degrees
over the total area of the large polycarbonate
headlight, thus removing reflections and allowing
maximum light transmission.
Specification
Substrate size: 350 mm x 220 mm (Oval)
Transmission: >99.5% over the total area
of the substrate
Angular range: 25 - 40 degrees
Durability: The coating must withstand the
MIL specifications: Mil-M-13508, temperature
cycling, adhesion, abrasion, and humidity.
Design Review
There were three difficulties to be solved
when designing the coating for these headlight
covers:
1) The distribution of the coating:
Owing to the physical size of the substrates
the distribution mask within the chamber had
to be designed to achieve a homogenous coating.
2) The material type: The headlight
was made from polycarbonate - a light and very
strong material. Consequently, the deposition
technique had to operate at low temperature.
In addition, the coating had to have high durability
to withstand the harsh environment of being
on the front of a high performance car for the
duration of a 24 hour race. The technology chosen
to achieve this combination of low temperature
deposition and high durability was plasma assisted
deposition using our APS plant.
To
find out more about this technology click here
3) The angular specification on the coating
design: Our design package, Essential Macleod,
was used to ensure the design would operate
at <0.5% reflection between 25 degrees and
40 degrees.
This same rigorous development process is applied
to all of our coatings whether they are for
a new standard process or a one-off customer
special.
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C and we can deposit this coating onto
temperature sensitive substrates.