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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3390
Loc: Northeast
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Just a suppose, but if I wanted to make a doublet using quartz, where could I get a piece or two with 1/2" thickness at 4.5-6" diameter?
How is a piece graded for lens use?
Mark
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So many projects, so little time!
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ed_turco
member
Reged: 08/29/09
Posts: 95
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Quartz suitable for lens work is called "Dynasil". A piece from one of the outlets is going to cost a pretty penny but you might pick up something from SS. Hope this helps.
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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 2312
Loc: salem, OR
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Mark,
Chris at RecoLabs has, among many 14.7x.8" fused silica pieces, a small % that pass refractive tests for me...place the quasi plano-plano part in front of a mirror under test on the stand and look at the Ronchi bands. The ones that show Ronchi bands are transmission grade, IMO, and a few of these parts have been sold for lens work (all quartz Schupmans, mostly), but there aren't any reports about utility.
I asked him to sort out a few of these when he has the time, I'm interested in getting them as well. It might work for you. They can be waterjetted to size.
Best,
Mark
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3390
Loc: Northeast
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Ed, I wonder if what you're calling "Dynasil" is what we used to call "Excimer"(sp?) I know that stuff would make a lens, but it was very scarce, likely not attainable by some idiot like me experimenting.
Mark, do you put the stuff right up to the mirror? I have 3 pieces from Chris, but they are way off of flat, and somewhat irregular; so wouldn't likely show meaningful bands anyway. ???
M.
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So many projects, so little time!
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kfrederick
scholastic sledgehammer
Reged: 02/01/08
Posts: 778
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MARK maybe check with RAY at n------ glass .What you making??
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Gregory Rohde
Vendor (Superior Optical Supply)
Reged: 05/02/07
Posts: 53
Loc: Portland Oregon
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Mark -
I have several pieces that were end cuts from 6.1" and 7.0" cores that are .4 - .75" thick. And ALL of my "N" type quartz is refractive grade.
Bear in mind though that quartz has a low index of refraction. All of the pieces that I have sold in the past for lenses have been pretty thick to account for a steep curve.
Greg
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mark cowan
Vendor (Obsidian Optics)
Reged: 06/03/05
Posts: 2312
Loc: salem, OR
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Quote:
Mark, do you put the stuff right up to the mirror? I have 3 pieces from Chris, but they are way off of flat, and somewhat irregular; so wouldn't likely show meaningful bands anyway. ???
M.
Right, and I've only done this to compare a couple of plano-plano (polished both sides) pieces. The surface on those parts is at least a couple waves, so if I saw wavy but intact lines I consider it good. The stuff with micro-bubbles (shows a laser track) showed a complete mess on transmission.
The reason I didn't mention Greg's material is I haven't personally tested any of it for transmission quality, as I've only had it here unpolished, and for the same reason I can't get a laser into it to check for bubbles. But if he says it's refractive grade I'd take it as true, wouldn't be that hard to test before finishing a piece, anyway. 
If the lenses you're talking about are for a Chief I know Ed said the lenses could be fairly thin in quartz, and you could build an all-quartz Chief. 
Best,
Mark
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1476
Loc: Sin-sin-atti
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United Lens Co. has fused quartz but it will be more expensive.
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Ed Jones
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