When most people think about Arizona Stadium, the first thing that comes to mind is football. However for 11 UBRPers, the Steward Observatory Mirror Lab
may be the first thought that comes to mind. With the Wildcats playing about seven regular season games a year, the majority of the action at Arizona Stadium happens under the East Wing.

On August 5, we were given the opportunity to attend a presentation and tour of the Steward Observatory Mirror Lab. Volunteer tour guide Vern Dunlap gave us a fact-filled presentation and showed a video of the history and the process from start to finish. A tour from the catwalk suspended above the lab gave us a first hand view of the equipment, tools, and polishing process of an LBT mirror.

The Mirror Lab has been housed in the East Wing since 1985 and is funded in part by the U.S. Air Force and the National Science Foundation along with the University of Arizona. Led by Dr. Roger Angel, a new design and manufacturing process has allowed for the production of Large Binocular Telescope (LBT) mirrors.

Dr. Angel’s new honeycomb design began in his garage laboratory in the 1980s. The interior honeycomb allows the LBT mirrors, which currently range from 1.2 meters to 8.4 meters, to weigh much less than solid glass mirrors of similar dimensions. Another advantage of the honeycomb is its ability to allow air to circulate around the mirror, equalizing the temperature of the mirror to match more closely the night temperatures and thereby, provide crisp images.

The borosilicate material begins as sand in Florida, travels to Japan where it is fired in clay jars, and finally is shipped to the mirror lab in approximately five pound pieces of glass where the manufacturing process commences. In giant jigsaw puzzle fashion, each piece of glass undergoes inspection before it is placed on the prepared mold resting in the furnace. Once the puzzle is complete the top of the furnace is lowered in place with an overhead crane. For the 8.4-meter mirror, the three-month spin casting begins, yielding the requisite parabolic shape. What follows is extensive grinding and polishing to exact specifications before the LBT mirror is shipped to its final destination. Once there it will receive its aluminum coating resulting in a final product.

During the tour, we were fortunate to see some of the extensive polishing taking place on the second LBT mirror destined for the Mt. Graham Observatory. We were also able to wander around the giant furnace top all the while taking care of the cables snaking out of the furnace top. The cameras and the adjustable opening along the top were visible and explained some of the pictures seen on the video.

Thanks to volunteer tour guides, Vern Dunlap
and Dan Schultz, and to UBRPer Daniel Wood for organizing the tour, a handful of UBRPers were given a peek at the action under the stadium.

Rachel Diaz, UBRPer in Dr. Margaret Smith’s lab, Biochemistry & Molecular Biophysics