Re: [ATM] Vacuum coating, was Silvering Woes

[hermit <hermit@outofoptions.org>]

James Lerch wrote:

>----- Original Message ----- 
>From: "Jason Hissong" <jhissong@gmail.com>
>
>
>  
>
>>James,
>>
>>We may be getting an old vacuum chamber going again up at the observatory 
>>where we do mirror making sessions.  We need to get a new diffuser pump and 
>>such. But I had a question in regards to the protective coating.  How do you 
>>put a coating of protective silicon over the aluminum?  In a similar fashion?
>>    
>>
>
>Well, I don't 'YET' :)
>
>Personally I feel that a non overcoated surface appears to provide a performance 
>boost in contrast.  But it is just a feeling based on observation of a few 
>mirrors I coated for club members, who later had the same optic professionally 
>coated.
>
>Like I said in the beginning, it is just a 'FEELING', devising a method to test 
>this condition is beyond my abilities, 
>
There was a discussion about this a while ago.  I think one person who 
knew some one in the business claimed the overcoating was a good 'money 
maker' but did degrade optical performance.

I'm not going to take the time to search this one because coming up with 
the reference without more keywords, like remembering the author, would 
be too hard.  Just saying that some past observations would support 
this.  I don't remember contrast being a specific criteria.  Just 
general scatter.

ken
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