Back to Home

ATM Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Amateur Telescope Making | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Localized

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Robert May on August 16, 2002 18:44:29 UTC

Nope, the differential expansion works for any surface. I might also note that the difference between a slumped sphere and paraboloid is measured in microns and that is a very small dimension! The difference between the front and back for a slumped piece of glass would be more dependant upon the grinding rather than the polishing and figuring. You could have the center thicker or thinner, depending upon the end result of grinding.
As to the particular glass, I'd still want to use pyrex for it's smaller deformation with temp anyway.

Follow Ups:

    Login to Post
    Additional Information
    Google
     
    Web www.astronomy.net
    DayNightLine
    About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
    Unless otherwise specified, web site content Copyright 1994-2020 John Huggins All Rights Reserved
    Forum posts are Copyright their authors as specified in the heading above the post.
    "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
    are trademarks of John Huggins