ALUMINUM:
Aluminum mirrors and variable density filters are
available in standard and custom sizes on glass, plastic, and silicon
wafers. The opacity or optical density of a film is a function of film
thickness. Figure 1 presents film transmission and optical density as a
function of film thickness. For films of sufficient thickness (greater
than a few hundred angstroms), the reflection of recently deposited
aluminum is essentially constant. Aluminum will oxidize over time and
reflectivity will degrade. An overcoat of magnesium fluoride is
available for protection of the aluminum film against oxidation. Figure
2 presents visible reflection in the visible for both freshly deposited
aluminum and protected aluminum.
Mirrors, optical density filters, and variable density transmission
filters are available on standard glass and plastic substrates. We also
offer wafer aluminizing services.
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Figure 1: The transmission through a
thin aluminum film is a function of film thickness. We fabricate
standard and custom filters with variable transmission and reflection.
Applications include selective attenuation of laser sources or improved
uniformity of light sources.
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Figure 2: At sufficient thickness, the
reflectivity of an aluminum mirror is essentially independent of
further increases in film thickness, however, the mirror oxidizes over
time. A protective overcoat can be added to extend the life of the
mirror. Reflectivity of a protected aluminum film, relative to a
freshly coated aluminum film, is plotted versus wavelength. A loss in
visible reflectivity of about 3% can be expected.
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Click here to request more information regarding
our coating capabilities and thin film products.