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Lenses were shipped from Cleveland Crystals a little earlier than expected (by Fed Ex White Glove) and Charlie confirmed they arrived OK in Pittsburgh a few hours later. This is an edge view of the corrector lens showing the shipping fixture built to transport the coated lens from Cleveland to Pittsburgh. In the ![[WWW]](/wiki/img/moin-www.gif "[WWW]"){kind=small}
bigger picture you can see the effect of the lens coating.
Charlie Hull and I spent last Thursday (Feb 12, 2004) at Cleveland Crystals to examine the lenses and discuss the dipping process.
Dian Nutter did a stand-up presentation after which we discussed with Charlie Hull the mounting of the lenses. There was considerable discussion about the lens cleaning process; perhaps the edge of the cell could be dammed with something or the centering screws could be removed to allow the fluid to drain.
We inspected the lenses in the cleanroom. Both lenses have shallow drill marks, possibly to block a fracture or clear a bubble. One of the lenses (at least) has generating marks on it; a pair of off-center circles about 7 or 8 inches in diameter. More like machine marks than scratches from a piece of grit, but it's hard to know. We decided not to do anything special about the drill marks beyond orienting the lens so drips would be least offensive; any drips would be considered cosmetic defects. Dian believes that the pull rate on the lens would be so slow that drips would not really have time to form.
She showed us the drums full of the coating liquid (also some smaller ones with material for the U Wisconsin job). The stuff is a low-viscosity solvent.
Dian showed us the lifting fixture. The lens holder is an aluminum ring lined with rubber to grab the lens. They will allow us to borrow it for installing the lens in the cells. We will return the band after installation.
Lift time is around 10 minutes. After drying for a while, the vapor tank is brought in and the lens is set in it overnight.
They use a Perkin-Elmer spectrophotometer to test witness samples, and have a portable Ocean spectrometer in a PC to measure the big lens.
More tour stops included the vacuum coating facilities (they're good at IR lenses), Solgel spin coating, and machine shop.
For the F/11 Gregorian focus on Baade. This lens set is now (Jan 2004) at Cleveland Crystals to be given a Solgel coating. The schedule as of Jan 23, 2004, is for a February 20, 2004 delivery.
I telephoned Robert Dew (Jan 15, 2004) about the wedge and keeping the edges clean of solgel (left voicemail). He returned my call and we had a good discussion about the process and details, including keeping an area on the lens faces clean of solgel. I asked Charlie to contact him and they had a good conversation. Charlie and I are planning to visit Cleveland Crystals on Thursday, February 12, 2004.
Charlie has some ideas, and after talking with Robert Dew has a better idea of what's going on.
Visited LCO during the week of Jan 19, 2004. Talked with Jose about the control systems in general and Silvia about the ADC software in particular. Since the motors are attached to the lens cells, full-up testing can't happen until the hardware is installed on the telescope. This will probably mean putting off use of the system until after installation. Current schedule suggests that the May 2, 2004 engineering run is the time to install, but we will wait until after our visit to Cleveland Crystals to make that official.
