Re: [ATM] suggestions wanted for 6 inch optical window

["Thomas Janstrom" <thomas@moiler.com>]

Yes, but what is a "type III" filter? 

I have one of these (plan is to use it as a window too) so what does it
filter out? UV? IR? ???? If it's either UV or IR I don't mind, but if it's
something towards the visual band then I don't know, it would seriously
depend on what and how much.

BTW the quality is very good, I haven't done any interference tests yet, but
mine has no visible blemishes....

OH yeah, thanks for the tip on the other disk, I need a blank about that
size (thickness is spot on) in BK7 for a 5" Schmidt corrector, at $29 its
right in my price range and most of the work is already done, too! 

Cheers, Thomas.

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Jarvis Krumbein
Sent: Sunday, 18 March 2007 7:30 AM
To: gilboastro@yahoo.com
Cc: atm@atmlist.net
Subject: Re: [ATM] suggestions wanted for 6 inch optical window

Gil, the 3/8 thick filter will ;probably be your best bet.  If ir was
manufactured as a filter it should be of good enough optical quality. 
Being the less expensive of the two choices doesn't hurt either.  Yes,
you can glue to the inside surface and the greater thickness of the
filter should help there.  Use a silicon adhesive such as are used for
fish tanks.

Good luck,

Jarvis Krumbein

On Sat, 17 Mar 2007 12:58:31 -0700 (PDT) Gil McFarlane
<gilboastro@yahoo.com> writes:
> I want to try putting an optical window at the front end of my 5" 
> f11.6 scope (I missed f12 by a few inches - oops).  I am thinking of 
> buying one or the following and then testing them/correcting them 
> rather than starting from scratch from a more expensive raw blank.  
> Plus, if I'm lucky, I may just need to polish it a little.
>    
>   One is a little thicker than the other:  3/8" vs. 6mm (about 
> 1/4").  One is "optical glass" the other is "BK7".  The cost 
> difference is not enough to worry about.  
>    
>   1.  Are either of these thick enough for a window (that will be 
> supporting the secondary too)?  
>    
>   2.  Is it possible to simply glue to the inside surface rather 
> than cutting a hole through?
>    
>    
>   Thanks, Gil
>   the glass is at:
>    
>   http://www.surplusshed.com/pages/item/pm1077.html
>    
>   http://www.surplusshed.com/pages/item/m1432.html
>    
>    
> 
>  
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