Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1 | 2 | 3 | 4 | (show all)
ccaissie
professor emeritus


Reged: 09/13/10

Loc: Whitefield, Maine
Re: Homemade Mylar Parabolic mirror new [Re: glennnnnnn]
      #5618041 - 01/11/13 09:20 PM

Quote:

What is stopping you from making a parabolic surface and sticking on the reflective coating?
(That's a rhetorical question- I know the answer.)




Wait dude! you're onto something!

Like grind and polish the shape into something like glass and float a thin layer of metal onto it! Wow!


Post Extras: Print Post   Remind Me!   Notify Moderator  
John Carruthers
Skiprat
*****

Reged: 02/02/07

Loc: Kent, UK
Re: Homemade Mylar Parabolic mirror new [Re: ccaissie]
      #5618415 - 01/12/13 03:22 AM

or cast the shape in resin then apply a film?
I doubt it would get to the quality we are used to obtaining but it's worth a try?


Post Extras: Print Post   Remind Me!   Notify Moderator  
glennnnnnn
sage


Reged: 10/20/09

Loc: San Diego, CA
Re: Homemade Mylar Parabolic mirror new [Re: ccaissie]
      #5618856 - 01/12/13 11:26 AM

Quote:

Quote:

There are plenty of failed projects out there, you can be sure that Henry [Ford] had his share. I have worked on a few myself.




Now, that's a knee-slapper.

I see the Mylar parabolic idea as a solar concentrator, not suitable for imaging at my level of technical expertise.

Murphy's law...."Everybody has at least one idea that won't work."




All sorts of people working to create and invent something better, and you know that so many things come about because a guy was just doofing around and... (example: A falling apple hits him on the head!)
In between Great Ideas you just go through the motions.

It might be a workable plan.
Grinding the base to attach the mylar is in the works, along with a whole zoo of other projects!
-An alloy bicycle rim for a strong edge, and many possibilites for the base-material.
-Grinding the surface out, just like grinding a mirror would probably work better.
-Once the surface is good enough you can make a mold and cast duplicates.
-The vacuum part is just to attach the mylar to the base with spray adhesive.

Edited by glennnnnnn (01/12/13 11:46 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Polymer Mirrors new [Re: John Carruthers]
      #5619018 - 01/12/13 12:53 PM

Quote:

or cast the shape in resin then apply a film?
I doubt it would get to the quality we are used to obtaining but it's worth a try?




This thread has touched on a number of proposals for exotic mirror technologies - the Mylar/air pressure system of the original post, liquid pillow mirrors, this one about using resin with a reflective film (though you could metallize it with more standard techniques), and even ultimate mirror technology using graphene film and diamond cells. All of these are types of polymer mirrors (if you rate graphene as being technically a polymer).

I wanted to point out that there is work being done now on carbon fiber/epoxy mirrors that are showing promising results:
http://www.compositemirrors.com/pub/spie/ULTRAOptics.pdf

What they are doing is (in effect) using a glass "inverse mirror" mirror as a mold, applying a layer of commercial pre-impregnated CF fabric/epoxy that is cured at 121 C under 15-30 psi. The composite mirror surface is generated by direct contact with the mold. The CF mirror surface thus produced is then glued to a composite "egg crate" cellular back for support.

They perfected their techniques with 16" F/4 mirrors, consistently getting 1/8 or so wavefront error mirrors, and are working on scaling up to a 1 meter mirror for a real telescope to be built.

Interesting side-note, the 16" mirror mold was made by Royce, their first system was a 6" made by Pegasus.

This technology is producing good mirrors of interesting size and focal ratio now - it looks like a promising area for the bold ATM'er (perhaps hoping to go commercial if successful) to take a crack at to see if these techniques could be adapted to the needs/budgets of amateur astronomers.

Since normal mirror making naturally creates a spherical inverse mirror tool you could start with this for experiments, without worrying about parabolizing.

Another possibility is to use a regular mirror as your starting point, and cast a mold that is then used for the mirror lay-up. Some research and experimentation would probably be called for to find a good castable mold material that will transfer the mirror surface accurately (and not stick to the CF prepreg).

Edited by careysub (01/12/13 01:55 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
glennnnnnn
sage


Reged: 10/20/09

Loc: San Diego, CA
Re: Polymer Mirrors new [Re: careysub]
      #5619127 - 01/12/13 02:02 PM

As the idea(s) take form there are more materials available. Hooray for R & D!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | (show all)


Extra information
10 registered and 21 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 7862

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics