Posts Made By: Steve Dodds

Jim,

Pardon me for jumping and plugging my own business, but I do coatings for astronomical mirrors. I will also test your mirror for free. I don't do re-figuring so if your mirror needs work it will have to be sent elsewhere. The testing consists of setting your mirror up in autocollimation with an optical flat and using a Ronchi tester. I can't provide a numerical result, but I can give you an expert opinion on the mirror's overall quality, and whether it's worth re-coating. See my website here on Astromart or goto nova-optical.com

Thanks

Steve Dodds

I ran your interferogram through my copy of Quick Fringe. I got slightly different numbers, probably because I ran the fringes right to the edge, including the slight turned edge.

P-V .33
RMS .052 (1/19)
Strehl .90

Interferometric analysis measures everything! If this mirror had been tested through a Foucault, it would probably show 1/10 wave or better.

Steve Dodds

Dear Rod, and the rest of the group,

I was sorry to hear about the problems you have been having with FedEx. You are the 3rd person in as many weeks to complain of the same thing. FedEx's home delivery only has the option of being signed by a person. They won't leave it in an obviously safe place, or with a neighbor, they won't even let you sign a release. USP allows their driver to use some common sense, so starting Monday, I will be using UPS for all of my non commercial customers.

Steve

Nova Optical

A friend of mime, Mike Clements owns this 70" The mirror was a prototype of the Hubble, made by Itek in the 70's. It is a lightweight fused silica cellular mirror. 70" diameter 12" thick and f/6!! It was 1 of 3 mirrors made, this one was dropped and the side was chipped, and it sat in a box for 30 years. Mike is looking for land now, and will be building the observatory in about a year.

George Kiger said:

The specs show coma = 0.1734 and very little astigmatism - I thought the RC was designed to have zero coma and a fair amount of astigmatism.

That refers to off-axis coma. Coma can also be present on axis. It is just like astigmatism except it runs in only one direction.

Steve Dodds