The University of Arizona

LBT #1 Polishing

The 8.4 meter mirror blank was then moved into the polishing lab in the nadir-pointing position. Grinding (generating) and polishing of the flat back surface of the blank began in January 1999 and was completed in June 1999. The permanent load spreaders were bonded to the back of the mirror with RTV during the last few months of 2000. In parallel, the 8.4m polishing cell was prepared to accept the mirror. The 8.4m mirror was installed onto the polishing cell in March 2001.

Grinding (generating) on the parabolic front side of the 8.4 meter mirror began in August 2001 and was completed in October 2001. After converting the LOG to the stressed lap configuration, loose abrasive lapping of the generated surface began in January 2002. At the same time, the infrared (10 micron) null corrector was installed in the test tower to measure the ground surface.

The pitch on the stress lap used to polish LBT #1.