An important fact to consider when using Al as a reflective layer is the
environment in which it will be used.  Most homemade Al mirrors will
oxidize very quickly and their reflectance will change depending upon
humidity.  We have used uncoated Al mirrors and have had them lose >10%
reflectivity in a week due to exposure to humidity in the ambient air.

> At the link below you find a model of Al reflectance vs. thickness on Si
> (100 microns) using film star. The three lines are 600, 700, and 800 nm from
> top to bottom. The second graph is the same model with Ag for comparison.
> The third is reflectance vs. wavelength for Ag and Al, notice the dip in the
> Al due to Al's absorptance peak at 800nm. You need very little Al to reach
> your peak reflectance, the curve is basically flat from this point on. These
> were modeled using Filmstar.


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|                        N e l s   O s t r o m                            |
|                           ostrom@uiuc.edu                               |
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|                        Graduate Research Assistant                      |
|                        Optical Physics and Engineering                  |
|    oooO                Dept. of Electrical and Computer Engineering     |
|    (   )     Oooo                                                       |
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