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Re: Well Al Tell Us How...

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Posted by Al Misiuk on February 8, 2001 03:41:55 UTC

Hi Rick,
I have the equipment to both do the coatings and
measure the results.
I'm using a CHA600 vacuum deposition system with
a roughing pump and a cryopump.
I begin with a coating of about 150 nanometers
of silver which by itself can achieve about
95% reflectivity.
It is then followed by 7 quarter wavelengths of
alternating layers of magnesium fluoride and
zirconium dioxide. Those 7 layers constitute
the the dialectric coatings which more than than
makes up for the additional 3-4% of the reflection
Its important to go slow on the Electron-beam
doing the evaporating of the zirconium dioxide.Too
fast results in the decomposition of the oxygen
from the zirconium. The high heat from the the
zirconium dioxide evaporation helps in toughning the magnesium fluoride by breaking down its
crystalline structure. A sample slide is coated
so as to fit within a Perkin Elmer spectrometer
equipped to measure reflectance across 200nm
to 1100nm. Al

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