Optical flats: Where can I get them?

[Star Hunter]

I'm going to build a folded refractor for my 19th century Wray (London) 6" F15 lens. The parts I need are 4" and 3" dia. 1/20 wave optical flats - round or square. Any one got any pointers on where I can suss out these items?

cheers,

James

[multiweb (Marc)]

Originally Posted by Star Hunter

I'm going to build a folded refractor for my 19th century Wray (London) 6" F15 lens. The parts I need are 4" and 3" dia. 1/20 wave optical flats - round or square. Any one got any pointers on where I can suss out these items?

cheers,

James

Maybe edmund optics? Optical flats are quite expensive.

[Star Hunter]

I going to build a folded refractor for my 19th century Wray (London) 6" F15 lens. I need to get a 4" and 3" 1/20 wave flat mirrors that will be later Al. coated. Anyone know where I can these flats?

Thanks,

James

[Star Hunter]

Originally Posted by multiweb

Maybe edmund optics? Optical flats are quite expensive.

Saw this.. http://www.edmundoptics.com/optics/o...r=asc#products and the price!!!!!

[MrB (Simon)]

Have you checked SurplusShed? If they don't have any on their site, worth emailing them as I have read that the lucky people that are able to visit the store(USA) find things on the shelf that are not listed on the site.

They have a 79mm uncoated flat listed for $25(!!), but 1/10 wave: http://www.surplusshed.com/pages/item/l10768.html
They also list some 1/20 wave flats but too small, worth emailing them.

[Merlin66 (Ken)]

What about large Dobbie secondary mirrors?
They are available in quite large sizes??

[gbeal]

My suggestion too, like Ken says, use a newt secondary.
Gary

[anj026]

You might try Nova Optical.

http://www.nova-optical.com/Flat%20Mirrors.htm

[OzEclipse (Joe Cali)]

James

A cheap newt secondary, especially a mass produced Dob type is unlikely to be 1/20 wave.

A google search for optical flats gives numerous suppliers : -

http://www.customscientific.com/flats.htm

http://opticalflats.com/ofpricelist.html

http://www.advancedoptics.com/optica...gle-sided.html

The optical flats need to be bigger than the cross section of the light cone they are reflecting to avoid vignetting.

You can always make your own. You need 3 x 4 inch blanks. I'd work in 10mm plate glass as it's already pretty flat to start with and clear both sides for testing.


Best of luck

Joe

[Merlin66 (Ken)]

Not cheap...but to a spec. Some of the secondaries are quoted as 1/10 wave....

[MrB (Simon)]

Originally Posted by OzEclipse

A cheap newt secondary, especially a mass produced Dob type is unlikely to be 1/20 wave.

As Ken has said, not cheap(realistic IMO), but they do claim 1/20th.
http://www.astrosystems.biz/secm1.htm