Quote:
Originally Posted by Me2
Hmmm.... interesting discussion but my mirror is on it's way to Wayne and I need to make up my mind between the pros and cons of Aluminium + Quartz R>91% vs. Aluminium Enhanced R>95% coatings.
He intends to do my secondary at the same time. I seem to remember that secondaries should be enhanced. Is that correct?
Cheers,
Mark
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Just contacted Wayne to clarify the differences between his two Al coating techniques.
Looks like my previous description of Wayne's process was out of date or just wrong.
So:
Both use his low pressure ion assisted deposition method.
Both apply a 200nm aluminium layer.
The Aluminium + Quartz applies a 200nm layer of SiO2 as the overcoat.
The Aluminium Enhanced applies multiply layers of Titanium and Tantalum Oxides as the overcoat to a thickness of 15O nm.
Wayne says the enhanced coating is harder than the quartz coating although it is thiner of course.
As to which overcoat would protect the mirror better is a tough call.
Thiner/harder verses thicker/ softer.
Probably turn out to be the same.
gb.