LSST mirror cast

snowyskiesau · #1 03-09-2008, 10:45 AM

New mirror cast for the LSST. The article is a bit short on pictures but the one there is, is impressive.
I was going to post this in ATM-DIY forum but it seems a little ambitious for even the most advance amateur

Warning: If you click to download the picture, be prepared to wait. It's over 5MB.

erick (Eric) · #2 03-09-2008, 11:08 AM

It's got a hole in the middle of it!

snowyskiesau · #3 03-09-2008, 11:21 AM

They tried to hide that by filling it with people.
I hope they took their shoes off before walking on the glass.

I.C.D (Ian) · #4 03-09-2008, 12:00 PM

Did anyone click on to the photo? it took 3min for me to load the photo up .Two thing I did see was that the photo was taken about 2 or 3 past 12 and the people sitting in the middle are sitting on some sort of padding. Let hope they show how they will polish the mirrors with some photos
Ian.C

drmorbius (Randall) · #5 03-09-2008, 12:50 PM

How many teflon strips would you need to keep that dob from sticking?

Satchmo · #6 03-09-2008, 04:15 PM

A few things of interest about the fabrication and polishing of these 8.4 meter mirrors.

The parabolic curve is spun cast in the surface good to a mm or so.

Then the diamond milling with spinning cutter is so precise that thay only need then to lap the surface with 1 grinding powder , 12 micron abrasive befor they go straight to polish.

The large polishing tools contain hundreds of computer controlled motors which constantly bend the polishing tool as it passes over the surface and keep the polisher in total contact with the strongly aspheric shape of the mirror.