Mirror Vendors - who's got best quality for $$

Started by dsummers, 10/08/2002 02:49AM
Posted 10/08/2002 02:49AM Opening Post
Hi All,

I'm interested in procuring a large (22") fast (f3.7) mirror for an ATM project. I don't want to make the mirror myself, so I'm going commercial for it. I've looked at most everyone, and I'm noticing a price "pecking" order of (lowest to highest) Swayze, Nova, Pegasus, Galaxy, Intermountain Optics, and Torus. The order isn't necessarily important, but quality is to me. Is anyone aware of actual independent testing done on these vendors' products? I'm weary of all the bickering over wavefront quality claims...especially since they are so hard to verify (outside of a star test which is often seeing limited and incorporates total system error). The price difference between Nova (Ronchi) and Torus (interferometry) is $2K (which is 56% markup). I don't mind paying for quality, but I don't know how to verify it and level the playing field. I'd like to get a fine optic and expect to pay a fair price. Ideas, opinions, and/or comments?

Thanks!
Posted 10/08/2002 12:14PM #1
I saved this excerpt from a comment made by Allan Rahill a couple years back, on SAA if I recall correctly:

"I tested Zambuto... and they are really exceptional.... better than 1/10 wave. I tested two Swayze and they were about 1/5 wave... with micro ripples. I tested two 20" galaxy mirrors at 1/3 wave!!!! Surprise! The best mirrors I tested recently were Nova and Zambuto. Very smooth and no TDE, no zones... really nice."

That said, I used to own a 16" f/5 Swayze mirror that was better than those Allan described--a really nice mirror. I wouldn't hesitate to buy a mirror without an interferogram from Nova, Swayze or Pegasus.
Posted 10/08/2002 10:53PM #2
Thanks Ed (and everyone),

I think you're right; Vaughn seems very responsive (he is even willing to do interferometric tests for a fair price). I've also had very good response from Pegasus. I suspect that both these vendors produce excellent optics; a coin toss is probably required to finalize the decision! To be fair, the other companies are probably also good; I just didn't get the same responsiveness on my particular optic out of the other vendors. I'm not a fan of the divergent quality claims however, I think the industry should try and rally around a single number (strehl?). Vaughn quotes SURFACE RMS while Pegasus quotes WAVEFRONT RMS. This is very confusing (and probably gets Intermountain some business from time to time when it's really a wash). In any case, I don't think it's intentional; probably just convenient.

Thanks for venturing an opinion.

Doug