The aluminizing system for the 8.4 meter diameter LBT primary mirrors

The recently commissioned system for aluminizing the 8.408 meter diameter Large Binocular Telescope mirrors has a variety of unusual features. Among them are aluminizing the mirror in the telescope, the mirror is horizon pointing when aluminized, boron nitride crucibles are used for the sources, only 28 sources are used, the sources are powered with 280 Volts at 20 kHz, high vacuum is produced with a LN2 cooled charcoal cryo-panel, an inflatable edge seal is used to isolate the rough vacuum behind the mirror from the high vacuum space, and a burst disk is mounted in the center hole to protect the mirror from overpressure. We present a description of these features. Results from aluminizing both primary mirrors are presented.