Coating Processes
DSI has implemented four separate systems to accommodate the varied and often
rigorous demands placed on thin film coatings. This complete toolbox gives us
the ability to provide unique solutions, higher performance, increased volume,
and more durability in our coatings.
The MicroDyn® process is a short throw reactive sputtering process that is
proprietary to DSI and is the subject of a number of patents. The process is
highly flexible, with the capability to deposit metal oxides, nitrides, mixed
materials with fixed or graded compositions, rugates, metals, ITO, and
semiconductor materials. The coatings are highly durable and with the capability
to operate at temperatures as high as 1100°C, they can withstand the thermal
shock of direct transition from liquid nitrogen to boiling water. Coatings by
MicroDyn® have essentially zero wet-to-dry shifts. The process is capable of
highly precise filters, including narrow bandpass and other filters for telecom
applications. The MicroDyn® process can be operated at temperatures as low as
100°C, and is capable of deposition on engineering plastics and fiber optic
cables. Coatings can be applied even to highly convex and concave surfaces such
as lamp burners and reflectors with no loss of durability or performance.
MicroDyn® coatings, including complex filters, can be patterned using both
masking and photolithography techniques.
The LPCVD process is a thermally driven organometallic process that is currently
configured to deposit multi-layers of silicon dioxide, tantalum oxide, and
titanium dioxide as needed. The LPCVD process is useful for coating almost all
optical glasses, crystalline materials, ceramics, and metals. The unique aspect
of the LPCVD process is its capability to uniformly coat all surfaces of even
the most complex shapes with a high quality multi-layer optical coating. Like
the MicroDyn® process, the IsoDyn™ LPCVD process provides coatings with service
temperatures as high as 800°C, and with high resistance to thermal shock. The
LPCVD process is fully automated and is capable of manufacturing complex
filters.
DSI’s PECVD process uses a high intensity microwave source to drive the plasma
that provides the energy for deposition. The PECVD process is capable of
depositing metal oxides, nitrides, and semiconductor materials. The unique
aspect of the PECVD process is that it allows deposition on the inside (or
outside) surface of a tube or cylinder. As with the MicroDyn® and LPCVD
processes, the coatings produced are capable of operating at temperatures as
high as 800°C and withstanding severe thermal shock.
DSI's evaporative coating chambers are used for complex infrared coatings.
Advanced thin film designs are deposited in precision, cryo-pumped vacuum
chambers using electron beam guns and resistance sources with the option of ion
assist. Coatings are stable, can be laser and nuclear hardened, have minimum
scatter and absorption, are space-qualified, and meet all applicable military
specifications. Evaporation is especially efficient for depositing complex
multilayer interference coatings on flat and slightly curved substrates.
Infrared coatings with spectral performance requirements out to 25 µm in
wavelength can be produced. Typical applications are longwave passes, shortwave
passes, narrow bandpasses, beamsplitters, and anti-reflection coatings. Metals,
metal oxides, dielectrics and semiconductors are deposited on various
substrates, some of which include glass, silicon, germanium, zinc sulfide, and
zinc selenide.
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